diff --git a/content/base/src/nsContentUtils.cpp b/content/base/src/nsContentUtils.cpp
index 9a7694109030..69832c6d345f 100644
--- a/content/base/src/nsContentUtils.cpp
+++ b/content/base/src/nsContentUtils.cpp
@@ -505,8 +505,6 @@ nsContentUtils::InitializeEventTable() {
     { &nsGkAtoms::onMozRotateGesture,            { NS_SIMPLE_GESTURE_ROTATE, EventNameType_None } },
     { &nsGkAtoms::onMozTapGesture,               { NS_SIMPLE_GESTURE_TAP, EventNameType_None } },
     { &nsGkAtoms::onMozPressTapGesture,          { NS_SIMPLE_GESTURE_PRESSTAP, EventNameType_None } },
-
-    { &nsGkAtoms::ontransitionend,               { NS_TRANSITION_END, EventNameType_None }},
   };
 
   sEventTable = new nsDataHashtable<nsISupportsHashKey, EventNameMapping>;
diff --git a/content/base/src/nsGkAtomList.h b/content/base/src/nsGkAtomList.h
index 675b5c6eb852..a56787921c27 100644
--- a/content/base/src/nsGkAtomList.h
+++ b/content/base/src/nsGkAtomList.h
@@ -678,7 +678,6 @@ GK_ATOM(onselect, "onselect")
 GK_ATOM(onset, "onset")
 GK_ATOM(onsubmit, "onsubmit")
 GK_ATOM(ontext, "ontext")
-GK_ATOM(ontransitionend, "ontransitionend")
 GK_ATOM(onunderflow, "onunderflow")
 GK_ATOM(onunload, "onunload")
 GK_ATOM(open, "open")
diff --git a/content/events/public/nsIPrivateDOMEvent.h b/content/events/public/nsIPrivateDOMEvent.h
index de50ca1acdbb..b71eb03824b7 100644
--- a/content/events/public/nsIPrivateDOMEvent.h
+++ b/content/events/public/nsIPrivateDOMEvent.h
@@ -115,6 +115,4 @@ nsresult
 NS_NewDOMSimpleGestureEvent(nsIDOMEvent** aInstancePtrResult, nsPresContext* aPresContext, class nsSimpleGestureEvent* aEvent);
 nsresult
 NS_NewDOMScrollAreaEvent(nsIDOMEvent** aInstancePtrResult, nsPresContext* aPresContext, class nsScrollAreaEvent* aEvent);
-nsresult
-NS_NewDOMTransitionEvent(nsIDOMEvent** aInstancePtrResult, nsPresContext* aPresContext, class nsTransitionEvent* aEvent);
 #endif // nsIPrivateDOMEvent_h__
diff --git a/content/events/src/Makefile.in b/content/events/src/Makefile.in
index ea0e17863c2f..e009fa0f7f94 100644
--- a/content/events/src/Makefile.in
+++ b/content/events/src/Makefile.in
@@ -81,7 +81,6 @@ CPPSRCS		= \
 		nsDOMSimpleGestureEvent.cpp \
 		nsDOMEventTargetHelper.cpp \
 		nsDOMScrollAreaEvent.cpp \
-		nsDOMTransitionEvent.cpp \
 		$(NULL)
 
 # we don't want the shared lib, but we want to force the creation of a static lib.
diff --git a/content/events/src/nsDOMEvent.cpp b/content/events/src/nsDOMEvent.cpp
index 41a784b16362..248df57ba853 100644
--- a/content/events/src/nsDOMEvent.cpp
+++ b/content/events/src/nsDOMEvent.cpp
@@ -92,8 +92,7 @@ static const char* const sEventNames[] = {
   "MozRotateGesture",
   "MozTapGesture",
   "MozPressTapGesture",
-  "MozScrolledAreaChanged",
-  "transitionend"
+  "MozScrolledAreaChanged"
 };
 
 static char *sPopupAllowedEvents;
@@ -706,10 +705,6 @@ nsDOMEvent::SetEventType(const nsAString& aEventTypeArg)
     else if (atom == nsGkAtoms::onMozTapGesture)
       mEvent->message = NS_SIMPLE_GESTURE_TAP;
   }
-  else if (mEvent->eventStructType == NS_TRANSITION_EVENT) {
-    if (atom == nsGkAtoms::ontransitionend)
-      mEvent->message = NS_TRANSITION_END;
-  }
 
   if (mEvent->message == NS_USER_DEFINED_EVENT)
     mEvent->userType = atom;
@@ -1012,16 +1007,6 @@ NS_METHOD nsDOMEvent::DuplicatePrivateData()
       newEvent = simpleGestureEvent;
       break;
     }
-    case NS_TRANSITION_EVENT:
-    {
-      nsTransitionEvent* oldTransitionEvent =
-        static_cast<nsTransitionEvent*>(mEvent);
-      newEvent = new nsTransitionEvent(PR_FALSE, msg,
-                                       oldTransitionEvent->propertyName,
-                                       oldTransitionEvent->elapsedTime);
-      NS_ENSURE_TRUE(newEvent, NS_ERROR_OUT_OF_MEMORY);
-      break;
-    }
     default:
     {
       NS_WARNING("Unknown event type!!!");
@@ -1510,8 +1495,6 @@ const char* nsDOMEvent::GetEventName(PRUint32 aEventType)
     return sEventNames[eDOMEvents_MozPressTapGesture];
   case NS_SCROLLEDAREACHANGED:
     return sEventNames[eDOMEvents_MozScrolledAreaChanged];
-  case NS_TRANSITION_END:
-    return sEventNames[eDOMEvents_transitionend];
   default:
     break;
   }
diff --git a/content/events/src/nsDOMEvent.h b/content/events/src/nsDOMEvent.h
index 888a8fd3a639..c40ef0db8659 100644
--- a/content/events/src/nsDOMEvent.h
+++ b/content/events/src/nsDOMEvent.h
@@ -171,8 +171,7 @@ public:
     eDOMEvents_MozRotateGesture,
     eDOMEvents_MozTapGesture,
     eDOMEvents_MozPressTapGesture,
-    eDOMEvents_MozScrolledAreaChanged,
-    eDOMEvents_transitionend
+    eDOMEvents_MozScrolledAreaChanged
   };
 
   nsDOMEvent(nsPresContext* aPresContext, nsEvent* aEvent);
diff --git a/content/events/src/nsDOMTransitionEvent.cpp b/content/events/src/nsDOMTransitionEvent.cpp
deleted file mode 100644
index 5b1876cfb00a..000000000000
--- a/content/events/src/nsDOMTransitionEvent.cpp
+++ /dev/null
@@ -1,114 +0,0 @@
-/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is nsDOMTransitionEvent.
- *
- * The Initial Developer of the Original Code is the Mozilla Foundation.
- * Portions created by the Initial Developer are Copyright (C) 2009
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *   L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-#include "nsDOMTransitionEvent.h"
-#include "nsGUIEvent.h"
-
-nsDOMTransitionEvent::nsDOMTransitionEvent(nsPresContext *aPresContext,
-                                           nsTransitionEvent *aEvent)
-  : nsDOMEvent(aPresContext, aEvent ? aEvent
-                                    : new nsTransitionEvent(PR_FALSE, 0,
-                                                            EmptyString(),
-                                                            0.0))
-{
-  if (aEvent) {
-    mEventIsInternal = PR_FALSE;
-  }
-  else {
-    mEventIsInternal = PR_TRUE;
-    mEvent->time = PR_Now();
-  }
-}
-
-nsDOMTransitionEvent::~nsDOMTransitionEvent()
-{
-  if (mEventIsInternal) {
-    delete TransitionEvent();
-    mEvent = nsnull;
-  }
-}
-
-NS_INTERFACE_MAP_BEGIN(nsDOMTransitionEvent)
-  NS_INTERFACE_MAP_ENTRY(nsIDOMTransitionEvent)
-  NS_INTERFACE_MAP_ENTRY_CONTENT_CLASSINFO(TransitionEvent)
-NS_INTERFACE_MAP_END_INHERITING(nsDOMEvent)
-
-NS_IMPL_ADDREF_INHERITED(nsDOMTransitionEvent, nsDOMEvent)
-NS_IMPL_RELEASE_INHERITED(nsDOMTransitionEvent, nsDOMEvent)
-
-NS_IMETHODIMP
-nsDOMTransitionEvent::GetPropertyName(nsAString & aPropertyName)
-{
-  aPropertyName = TransitionEvent()->propertyName;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-nsDOMTransitionEvent::GetElapsedTime(float *aElapsedTime)
-{
-  *aElapsedTime = TransitionEvent()->elapsedTime;
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-nsDOMTransitionEvent::InitTransitionEvent(const nsAString & typeArg,
-                                          PRBool canBubbleArg,
-                                          PRBool cancelableArg,
-                                          const nsAString & propertyNameArg,
-                                          float elapsedTimeArg)
-{
-  nsresult rv = nsDOMEvent::InitEvent(typeArg, canBubbleArg, cancelableArg);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  TransitionEvent()->propertyName = propertyNameArg;
-  TransitionEvent()->elapsedTime = elapsedTimeArg;
-
-  return NS_OK;
-}
-
-nsresult
-NS_NewDOMTransitionEvent(nsIDOMEvent **aInstancePtrResult,
-                         nsPresContext *aPresContext,
-                         nsTransitionEvent *aEvent)
-{
-  nsDOMTransitionEvent *it = new nsDOMTransitionEvent(aPresContext, aEvent);
-  if (!it) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
-
-  return CallQueryInterface(it, aInstancePtrResult);
-}
diff --git a/content/events/src/nsDOMTransitionEvent.h b/content/events/src/nsDOMTransitionEvent.h
deleted file mode 100644
index 0c7006b9e4be..000000000000
--- a/content/events/src/nsDOMTransitionEvent.h
+++ /dev/null
@@ -1,66 +0,0 @@
-/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is nsDOMTransitionEvent.
- *
- * The Initial Developer of the Original Code is the Mozilla Foundation.
- * Portions created by the Initial Developer are Copyright (C) 2009
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *   L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-#ifndef nsDOMTransitionEvent_h_
-#define nsDOMTransitionEvent_h_
-
-#include "nsDOMEvent.h"
-#include "nsIDOMTransitionEvent.h"
-#include "nsString.h"
-
-class nsTransitionEvent;
-
-class nsDOMTransitionEvent : public nsDOMEvent,
-                             public nsIDOMTransitionEvent
-{
-public:
-  nsDOMTransitionEvent(nsPresContext *aPresContext,
-                       nsTransitionEvent *aEvent);
-  ~nsDOMTransitionEvent();
-
-  NS_DECL_ISUPPORTS_INHERITED
-  NS_FORWARD_TO_NSDOMEVENT
-  NS_DECL_NSIDOMTRANSITIONEVENT
-
-private:
-  nsTransitionEvent* TransitionEvent() {
-    NS_ABORT_IF_FALSE(mEvent->eventStructType == NS_TRANSITION_EVENT,
-                      "unexpected struct type");
-    return static_cast<nsTransitionEvent*>(mEvent);
-  }
-};
-
-#endif /* !defined(nsDOMTransitionEvent_h_) */
diff --git a/content/events/src/nsEventDispatcher.cpp b/content/events/src/nsEventDispatcher.cpp
index c3edf42700dc..2d9f32bb0bec 100644
--- a/content/events/src/nsEventDispatcher.cpp
+++ b/content/events/src/nsEventDispatcher.cpp
@@ -721,9 +721,6 @@ nsEventDispatcher::CreateEvent(nsPresContext* aPresContext,
     case NS_SIMPLE_GESTURE_EVENT:
       return NS_NewDOMSimpleGestureEvent(aDOMEvent, aPresContext,
                                          static_cast<nsSimpleGestureEvent*>(aEvent));
-    case NS_TRANSITION_EVENT:
-      return NS_NewDOMTransitionEvent(aDOMEvent, aPresContext,
-                                      static_cast<nsTransitionEvent*>(aEvent));
     }
 
     // For all other types of events, create a vanilla event object.
@@ -792,10 +789,6 @@ nsEventDispatcher::CreateEvent(nsPresContext* aPresContext,
     return NS_NewDOMPageTransitionEvent(aDOMEvent, aPresContext, nsnull);
   if (aEventType.LowerCaseEqualsLiteral("scrollareaevent"))
     return NS_NewDOMScrollAreaEvent(aDOMEvent, aPresContext, nsnull);
-  // FIXME: Should get spec to say what the right string is here!  This
-  // is probably wrong!
-  if (aEventType.LowerCaseEqualsLiteral("transitionevent"))
-    return NS_NewDOMTransitionEvent(aDOMEvent, aPresContext, nsnull);
 
   return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
 }
diff --git a/dom/base/nsDOMClassInfo.cpp b/dom/base/nsDOMClassInfo.cpp
index dd8ff6dd7d1b..c6181fca7541 100644
--- a/dom/base/nsDOMClassInfo.cpp
+++ b/dom/base/nsDOMClassInfo.cpp
@@ -234,7 +234,6 @@
 #include "nsPaintRequest.h"
 #include "nsIDOMNotifyPaintEvent.h"
 #include "nsIDOMScrollAreaEvent.h"
-#include "nsIDOMTransitionEvent.h"
 #include "nsIDOMNSDocumentStyle.h"
 #include "nsIDOMDocumentRange.h"
 #include "nsIDOMDocumentTraversal.h"
@@ -1367,8 +1366,6 @@ static nsDOMClassInfoData sClassInfoData[] = {
                            DOM_DEFAULT_SCRIPTABLE_FLAGS)
   NS_DEFINE_CLASSINFO_DATA(EventListenerInfo, nsDOMGenericSH,
                            DOM_DEFAULT_SCRIPTABLE_FLAGS)
-  NS_DEFINE_CLASSINFO_DATA(TransitionEvent, nsDOMGenericSH,
-                           DOM_DEFAULT_SCRIPTABLE_FLAGS)
 };
 
 // Objects that shuld be constructable through |new Name();|
@@ -3790,11 +3787,6 @@ nsDOMClassInfo::Init()
     DOM_CLASSINFO_MAP_ENTRY(nsIEventListenerInfo)
   DOM_CLASSINFO_MAP_END
 
-  DOM_CLASSINFO_MAP_BEGIN(TransitionEvent, nsIDOMTransitionEvent)
-    DOM_CLASSINFO_MAP_ENTRY(nsIDOMTransitionEvent)
-    DOM_CLASSINFO_EVENT_MAP_ENTRIES
-  DOM_CLASSINFO_MAP_END
-
 #ifdef NS_DEBUG
   {
     PRUint32 i = NS_ARRAY_LENGTH(sClassInfoData);
diff --git a/dom/base/nsDOMClassInfoID.h b/dom/base/nsDOMClassInfoID.h
index 1051a2e8d703..7fc9ed644e03 100644
--- a/dom/base/nsDOMClassInfoID.h
+++ b/dom/base/nsDOMClassInfoID.h
@@ -489,8 +489,6 @@ enum nsDOMClassInfoID {
 
   eDOMClassInfo_EventListenerInfo_id,
 
-  eDOMClassInfo_TransitionEvent_id,
-
   // This one better be the last one in this list
   eDOMClassInfoIDCount
 };
diff --git a/dom/interfaces/events/Makefile.in b/dom/interfaces/events/Makefile.in
index f7498ab1a73e..f311987adb5c 100644
--- a/dom/interfaces/events/Makefile.in
+++ b/dom/interfaces/events/Makefile.in
@@ -82,7 +82,6 @@ XPIDLSRCS =					\
 	nsIDOMNSMouseEvent.idl			\
 	nsIDOMOrientationEvent.idl              \
 	nsIDOMScrollAreaEvent.idl		\
-	nsIDOMTransitionEvent.idl		\
 	$(NULL)
 
 include $(topsrcdir)/config/rules.mk
diff --git a/dom/interfaces/events/nsIDOMTransitionEvent.idl b/dom/interfaces/events/nsIDOMTransitionEvent.idl
deleted file mode 100644
index ffbdfcbc5830..000000000000
--- a/dom/interfaces/events/nsIDOMTransitionEvent.idl
+++ /dev/null
@@ -1,55 +0,0 @@
-/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is nsIDOMTransitionEvent.
- *
- * The Initial Developer of the Original Code is the Mozilla Foundation.
- * Portions created by the Initial Developer are Copyright (C) 2009
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *   L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-#include "nsIDOMEvent.idl"
-
-/**
- * Transition events are defined in:
- * http://www.w3.org/TR/css3-transitions/#transition-events-
- * http://dev.w3.org/csswg/css3-transitions/#transition-events-
- */
-
-[scriptable, uuid(3e49ea4c-6f23-4aff-bd8f-e587edf514ec)]
-interface nsIDOMTransitionEvent : nsIDOMEvent {
-  readonly attribute DOMString           propertyName;
-  readonly attribute float               elapsedTime;
-  void               initTransitionEvent(in DOMString typeArg, 
-                                         in boolean canBubbleArg, 
-                                         in boolean cancelableArg, 
-                                         in DOMString propertyNameArg,
-                                         in float elapsedTimeArg);
-};
diff --git a/layout/base/nsPresContext.cpp b/layout/base/nsPresContext.cpp
index adbcb8d40df0..1393f85847cd 100644
--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -259,15 +259,7 @@ nsPresContext::~nsPresContext()
   NS_PRECONDITION(!mShell, "Presshell forgot to clear our mShell pointer");
   SetShell(nsnull);
 
-  if (mTransitionManager) {
-    mTransitionManager->Disconnect();
-  }
-
-  // Disconnect the refresh driver *after* the transition manager, which
-  // needs it.
-  if (mRefreshDriver) {
-    mRefreshDriver->Disconnect();
-  }
+  delete mTransitionManager;
 
   if (mEventManager) {
     // unclear if these are needed, but can't hurt
@@ -881,12 +873,6 @@ nsPresContext::Init(nsIDeviceContext* aDeviceContext)
   NS_ADDREF(mEventManager);
 
   mTransitionManager = new nsTransitionManager(this);
-  if (!mTransitionManager)
-    return NS_ERROR_OUT_OF_MEMORY;
-
-  mRefreshDriver = new nsRefreshDriver(this);
-  if (!mRefreshDriver)
-    return NS_ERROR_OUT_OF_MEMORY;
 
   mLangService = do_GetService(NS_LANGUAGEATOMSERVICE_CONTRACTID);
 
diff --git a/layout/base/nsPresContext.h b/layout/base/nsPresContext.h
index 564fca5c5f55..1c4b03702195 100644
--- a/layout/base/nsPresContext.h
+++ b/layout/base/nsPresContext.h
@@ -72,6 +72,7 @@
 #include "nsContentUtils.h"
 #include "nsIWidget.h"
 #include "mozilla/TimeStamp.h"
+#include "nsRefreshDriver.h"
 
 class nsImageLoader;
 #ifdef IBMBIDI
@@ -102,7 +103,6 @@ class nsUserFontSet;
 struct nsFontFaceRuleContainer;
 class nsObjectFrame;
 class nsTransitionManager;
-class nsRefreshDriver;
 class imgIContainer;
 
 #ifdef MOZ_REFLOW_PERF
@@ -233,7 +233,13 @@ public:
 
   nsTransitionManager* TransitionManager() { return mTransitionManager; }
 
-  nsRefreshDriver* RefreshDriver() { return mRefreshDriver; }
+  nsRefreshDriver* RefreshDriver() { return &mRefreshDriver; }
+
+  static nsPresContext* FromRefreshDriver(nsRefreshDriver* aRefreshDriver) {
+    return reinterpret_cast<nsPresContext*>(
+             reinterpret_cast<char*>(aRefreshDriver) -
+             offsetof(nsPresContext, mRefreshDriver));
+  }
 #endif
 
   /**
@@ -951,8 +957,8 @@ protected:
                                         // from gfx back to layout.
   nsIEventStateManager* mEventManager;  // [STRONG]
   nsILookAndFeel*       mLookAndFeel;   // [STRONG]
-  nsRefPtr<nsRefreshDriver> mRefreshDriver;
-  nsRefPtr<nsTransitionManager> mTransitionManager;
+  nsRefreshDriver       mRefreshDriver;
+  nsTransitionManager*  mTransitionManager; // owns; it aggregates our refcount
   nsIAtom*              mMedium;        // initialized by subclass ctors;
                                         // weak pointer to static atom
 
diff --git a/layout/base/nsRefreshDriver.cpp b/layout/base/nsRefreshDriver.cpp
index 80bb2e033593..e6c36da572dd 100644
--- a/layout/base/nsRefreshDriver.cpp
+++ b/layout/base/nsRefreshDriver.cpp
@@ -44,7 +44,6 @@
 #include "nsPresContext.h"
 #include "nsComponentManagerUtils.h"
 #include "prlog.h"
-#include "nsAutoPtr.h"
 
 /*
  * TODO:
@@ -57,8 +56,7 @@
 
 using mozilla::TimeStamp;
 
-nsRefreshDriver::nsRefreshDriver(nsPresContext *aPresContext)
-  : mPresContext(aPresContext)
+nsRefreshDriver::nsRefreshDriver()
 {
 }
 
@@ -172,7 +170,11 @@ nsRefreshDriver::ArrayFor(mozFlushType aFlushType)
  * nsISupports implementation
  */
 
-NS_IMPL_ISUPPORTS1(nsRefreshDriver, nsITimerCallback)
+NS_IMPL_ADDREF_USING_AGGREGATOR(nsRefreshDriver,
+                                nsPresContext::FromRefreshDriver(this))
+NS_IMPL_RELEASE_USING_AGGREGATOR(nsRefreshDriver,
+                                 nsPresContext::FromRefreshDriver(this))
+NS_IMPL_QUERY_INTERFACE1(nsRefreshDriver, nsITimerCallback)
 
 /*
  * nsITimerCallback implementation
@@ -183,34 +185,18 @@ nsRefreshDriver::Notify(nsITimer *aTimer)
 {
   UpdateMostRecentRefresh();
 
-  if (!mPresContext) {
-    // Things are being destroyed.
-    NS_ABORT_IF_FALSE(!mTimer, "timer should have been stopped");
-    return NS_OK;
-  }
-  nsCOMPtr<nsIPresShell> presShell = mPresContext->GetPresShell();
+  nsPresContext *presContext = nsPresContext::FromRefreshDriver(this);
+  nsCOMPtr<nsIPresShell> presShell = presContext->GetPresShell();
   if (!presShell) {
     // Things are being destroyed.
     StopTimer();
     return NS_OK;
   }
 
-  /*
-   * The timer holds a reference to |this| while calling |Notify|.
-   * However, implementations of |WillRefresh| are permitted to destroy
-   * the pres context, which will cause our |mPresContext| to become
-   * null.  If this happens, we must stop notifying observers.
-   */
   for (PRUint32 i = 0; i < NS_ARRAY_LENGTH(mObservers); ++i) {
     ObserverArray::EndLimitedIterator etor(mObservers[i]);
     while (etor.HasMore()) {
-      nsRefPtr<nsARefreshObserver> obs = etor.GetNext();
-      obs->WillRefresh(mMostRecentRefresh);
-      
-      if (!mPresContext || !mPresContext->GetPresShell()) {
-        StopTimer();
-        return NS_OK;
-      }
+      etor.GetNext()->WillRefresh(mMostRecentRefresh);
     }
     if (i == 0) {
       // This is the Flush_Style case.
diff --git a/layout/base/nsRefreshDriver.h b/layout/base/nsRefreshDriver.h
index a65cd44cba08..d767b99cb85d 100644
--- a/layout/base/nsRefreshDriver.h
+++ b/layout/base/nsRefreshDriver.h
@@ -49,8 +49,6 @@
 #include "nsCOMPtr.h"
 #include "nsTObserverArray.h"
 
-class nsPresContext;
-
 /**
  * An abstract base class to be implemented by callers wanting to be
  * notified at refresh times.  When nothing needs to be painted, callers
@@ -58,29 +56,19 @@ class nsPresContext;
  */
 class nsARefreshObserver {
 public:
-  // AddRef and Release signatures that match nsISupports.  Implementors
-  // must implement reference counting, and those that do implement
-  // nsISupports will already have methods with the correct signature.
-  //
-  // The refresh driver does NOT hold references to refresh observers
-  // except while it is notifying them.  
-  NS_IMETHOD_(nsrefcnt) AddRef(void) = 0;
-  NS_IMETHOD_(nsrefcnt) Release(void) = 0;
-
   virtual void WillRefresh(mozilla::TimeStamp aTime) = 0;
 };
 
-class nsRefreshDriver : public nsITimerCallback {
+/*
+ * nsRefreshDriver MUST ONLY be constructed as a sub-object of
+ * nsPresContext (since its reference counting methods forward to the
+ * pres context of which it is an mRefreshDriver)
+ */
+class nsRefreshDriver : private nsITimerCallback {
 public:
-  nsRefreshDriver(nsPresContext *aPresContext);
+  nsRefreshDriver();
   ~nsRefreshDriver();
 
-  // nsISupports implementation
-  NS_DECL_ISUPPORTS
-
-  // nsITimerCallback implementation
-  NS_DECL_NSITIMERCALLBACK
-
   /**
    * Return the time of the most recent refresh.  This is intended to be
    * used by callers who want to start an animation now and want to know
@@ -102,26 +90,18 @@ public:
    *     painting, and, correspondingly, which get notified when there
    *     is a flush during such suppression
    * and it must be either Flush_Style, Flush_Layout, or Flush_Display.
-   *
-   * The refresh driver does NOT own a reference to these observers;
-   * they must remove themselves before they are destroyed.
    */
   PRBool AddRefreshObserver(nsARefreshObserver *aObserver,
                             mozFlushType aFlushType);
   PRBool RemoveRefreshObserver(nsARefreshObserver *aObserver,
                                mozFlushType aFlushType);
-
-  /**
-   * Tell the refresh driver that it is done driving refreshes and
-   * should stop its timer and forget about its pres context.  This may
-   * be called from within a refresh.
-   */
-  void Disconnect() {
-    StopTimer();
-    mPresContext = nsnull;
-  }
-
 private:
+  // nsISupports implementation
+  NS_DECL_ISUPPORTS_INHERITED
+
+  // nsITimerCallback implementation
+  NS_IMETHOD Notify(nsITimer *aTimer);
+
   typedef nsTObserverArray<nsARefreshObserver*> ObserverArray;
 
   void EnsureTimerStarted();
@@ -133,9 +113,6 @@ private:
   nsCOMPtr<nsITimer> mTimer;
   mozilla::TimeStamp mMostRecentRefresh; // only valid when mTimer non-null
 
-  nsPresContext *mPresContext; // weak; pres context passed in constructor
-                               // and unset in Disconnect
-
   // separate arrays for each flush type we support
   ObserverArray mObservers[3];
 };
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index a9b2372fbb73..e6f7ab55ffdf 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -717,8 +717,7 @@ CSS_PROP_BORDER(
     border_left_color_value,
     X,
     CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED,
     Margin,
     mBorderColor.mLeft,
     eCSSType_Value,
@@ -774,8 +773,7 @@ CSS_PROP_BORDER(
     border-left-style-value,
     border_left_style_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
     Margin,
     mBorderStyle.mLeft,
     eCSSType_Value,
@@ -817,8 +815,7 @@ CSS_PROP_BORDER(
     border-left-width-value,
     border_left_width_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
     Margin,
     mBorderWidth.mLeft,
     eCSSType_Value,
@@ -866,8 +863,7 @@ CSS_PROP_BORDER(
     border_right_color_value,
     X,
     CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED,
     Margin,
     mBorderColor.mRight,
     eCSSType_Value,
@@ -923,8 +919,7 @@ CSS_PROP_BORDER(
     border-right-style-value,
     border_right_style_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
     Margin,
     mBorderStyle.mRight,
     eCSSType_Value,
@@ -966,8 +961,7 @@ CSS_PROP_BORDER(
     border-right-width-value,
     border_right_width_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
     Margin,
     mBorderWidth.mRight,
     eCSSType_Value,
@@ -1657,8 +1651,7 @@ CSS_PROP_MARGIN(
     margin-left-value,
     margin_left_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
     Margin,
     mMargin.mLeft,
     eCSSType_Value,
@@ -1700,8 +1693,7 @@ CSS_PROP_MARGIN(
     margin-right-value,
     margin_right_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
     Margin,
     mMargin.mRight,
     eCSSType_Value,
@@ -1966,8 +1958,7 @@ CSS_PROP_PADDING(
     padding-left-value,
     padding_left_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
     Margin,
     mPadding.mLeft,
     eCSSType_Value,
@@ -2009,8 +2000,7 @@ CSS_PROP_PADDING(
     padding-right-value,
     padding_right_value,
     X,
-    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER |
-        CSS_PROPERTY_REPORT_OTHER_NAME,
+    CSS_PROPERTY_APPLIES_TO_FIRST_LETTER,
     Margin,
     mPadding.mRight,
     eCSSType_Value,
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index ac6ac7b36a32..b313883994fb 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -370,35 +370,6 @@ nsCSSProps::GetStringValue(nsCSSFontDesc aFontDescID)
   }
 }
 
-nsCSSProperty
-nsCSSProps::OtherNameFor(nsCSSProperty aProperty)
-{
-  switch (aProperty) {
-    case eCSSProperty_border_left_color_value:
-      return eCSSProperty_border_left_color;
-    case eCSSProperty_border_left_style_value:
-      return eCSSProperty_border_left_style;
-    case eCSSProperty_border_left_width_value:
-      return eCSSProperty_border_left_width;
-    case eCSSProperty_border_right_color_value:
-      return eCSSProperty_border_right_color;
-    case eCSSProperty_border_right_style_value:
-      return eCSSProperty_border_right_style;
-    case eCSSProperty_border_right_width_value:
-      return eCSSProperty_border_right_width;
-    case eCSSProperty_margin_left_value:
-      return eCSSProperty_margin_left;
-    case eCSSProperty_margin_right_value:
-      return eCSSProperty_margin_right;
-    case eCSSProperty_padding_left_value:
-      return eCSSProperty_padding_left;
-    case eCSSProperty_padding_right_value:
-      return eCSSProperty_padding_right;
-    default:
-      NS_ABORT_IF_FALSE(PR_FALSE, "bad caller");
-  }
-  return eCSSProperty_UNKNOWN;
-}
 
 /***************************************************************************/
 
diff --git a/layout/style/nsCSSProps.h b/layout/style/nsCSSProps.h
index 2681824b6eaa..bcbb0d95c361 100644
--- a/layout/style/nsCSSProps.h
+++ b/layout/style/nsCSSProps.h
@@ -79,13 +79,6 @@
 // list.
 #define CSS_PROPERTY_IMAGE_IS_IN_ARRAY_0          (1<<6)
 
-// This is a property for which the computed value should generally be
-// reported as the computed value of a property of a different name.  In
-// particular, the directional box properties (margin-left-value, etc.)
-// should be reported as being margin-left, etc.  Call
-// nsCSSProps::OtherNameFor to get the other property.
-#define CSS_PROPERTY_REPORT_OTHER_NAME            (1<<7)
-
 /**
  * Types of animatable values.
  */
@@ -159,11 +152,6 @@ public:
   static const nsAFlatCString& GetStringValue(nsCSSProperty aProperty);
   static const nsAFlatCString& GetStringValue(nsCSSFontDesc aFontDesc);
 
-  // Get the property to report the computed value of aProperty as being
-  // the computed value of.  aProperty must have the
-  // CSS_PROPERTY_REPORT_OTHER_NAME bit set.
-  static nsCSSProperty OtherNameFor(nsCSSProperty aProperty);
-
   // Given a CSS Property and a Property Enum Value
   // Return back a const nsString& representation of the 
   // value. Return back nullstr if no value is found
diff --git a/layout/style/nsTransitionManager.cpp b/layout/style/nsTransitionManager.cpp
index 741dbb0d2059..51a38edd648c 100644
--- a/layout/style/nsTransitionManager.cpp
+++ b/layout/style/nsTransitionManager.cpp
@@ -52,8 +52,6 @@
 #include "nsCSSPropertySet.h"
 #include "nsStyleAnimation.h"
 #include "nsCSSDataBlock.h"
-#include "nsEventDispatcher.h"
-#include "nsGUIEvent.h"
 
 using mozilla::TimeStamp;
 using mozilla::TimeDuration;
@@ -335,12 +333,6 @@ nsTransitionManager::nsTransitionManager(nsPresContext *aPresContext)
 }
 
 nsTransitionManager::~nsTransitionManager()
-{
-  NS_ABORT_IF_FALSE(!mPresContext, "Disconnect should have been called");
-}
-
-void
-nsTransitionManager::Disconnect()
 {
   // Content nodes might outlive the transition manager.
   while (!PR_CLIST_IS_EMPTY(&mElementTransitions)) {
@@ -348,8 +340,6 @@ nsTransitionManager::Disconnect()
                                  PR_LIST_HEAD(&mElementTransitions));
     head->Destroy();
   }
-
-  mPresContext = nsnull;
 }
 
 static PRBool
@@ -791,7 +781,9 @@ nsTransitionManager::AddElementTransitions(ElementTransitions* aElementTransitio
  * nsISupports implementation
  */
 
-NS_IMPL_ISUPPORTS1(nsTransitionManager, nsIStyleRuleProcessor)
+NS_IMPL_ADDREF_USING_AGGREGATOR(nsTransitionManager, mPresContext)
+NS_IMPL_RELEASE_USING_AGGREGATOR(nsTransitionManager, mPresContext)
+NS_IMPL_QUERY_INTERFACE1(nsTransitionManager, nsIStyleRuleProcessor)
 
 /*
  * nsIStyleRuleProcessor implementation
@@ -890,38 +882,9 @@ nsTransitionManager::MediumFeaturesChanged(nsPresContext* aPresContext,
   return NS_OK;
 }
 
-struct TransitionEventInfo {
-  nsCOMPtr<nsIContent> mElement;
-  nsTransitionEvent mEvent;
-
-  TransitionEventInfo(nsIContent *aElement, nsCSSProperty aProperty,
-                      TimeDuration aDuration)
-    : mElement(aElement),
-      mEvent(PR_TRUE, NS_TRANSITION_END,
-             NS_ConvertUTF8toUTF16(nsCSSProps::GetStringValue(aProperty)),
-             aDuration.ToSeconds())
-  {
-  }
-
-  // nsTransitionEvent doesn't support copy-construction, so we need
-  // to ourselves in order to work with nsTArray
-  TransitionEventInfo(const TransitionEventInfo &aOther)
-    : mElement(aOther.mElement),
-      mEvent(PR_TRUE, NS_TRANSITION_END,
-             aOther.mEvent.propertyName, aOther.mEvent.elapsedTime)
-  {
-  }
-};
-
 /* virtual */ void
 nsTransitionManager::WillRefresh(mozilla::TimeStamp aTime)
 {
-  NS_ABORT_IF_FALSE(mPresContext,
-                    "refresh driver should not notify additional observers "
-                    "after pres context has been destroyed");
-
-  nsTArray<TransitionEventInfo> events;
-
   // Trim transitions that have completed, and post restyle events for
   // frames that are still transitioning.
   {
@@ -942,13 +905,6 @@ nsTransitionManager::WillRefresh(mozilla::TimeStamp aTime)
         ElementPropertyTransition &pt = et->mPropertyTransitions[i];
         if (pt.mStartTime + pt.mDuration <= aTime) {
           // This transition has completed.
-          nsCSSProperty prop = pt.mProperty;
-          if (nsCSSProps::PropHasFlags(prop, CSS_PROPERTY_REPORT_OTHER_NAME)) {
-            prop = nsCSSProps::OtherNameFor(prop);
-          }
-          events.AppendElement(
-            TransitionEventInfo(et->mElement, prop, pt.mDuration));
-
           et->mPropertyTransitions.RemoveElementAt(i);
         }
       } while (i != 0);
@@ -967,15 +923,6 @@ nsTransitionManager::WillRefresh(mozilla::TimeStamp aTime)
 
   // We might have removed transitions above.
   TransitionsRemoved();
-
-  for (PRUint32 i = 0, i_end = events.Length(); i < i_end; ++i) {
-    TransitionEventInfo &info = events[i];
-    nsEventDispatcher::Dispatch(info.mElement, mPresContext, &info.mEvent);
-
-    if (!mPresContext) {
-      break;
-    }
-  }
 }
 
 void
diff --git a/layout/style/nsTransitionManager.h b/layout/style/nsTransitionManager.h
index f9761c381522..c91bb81efc60 100644
--- a/layout/style/nsTransitionManager.h
+++ b/layout/style/nsTransitionManager.h
@@ -52,17 +52,16 @@ class nsCSSPropertySet;
 struct nsTransition;
 struct ElementTransitions;
 
+/**
+ * Must be created only as a sub-object of an nsPresContext (since its
+ * reference counting methods assume that).
+ */
 class nsTransitionManager : public nsIStyleRuleProcessor,
                             public nsARefreshObserver {
 public:
   nsTransitionManager(nsPresContext *aPresContext);
   ~nsTransitionManager();
 
-  /**
-   * Notify the transition manager that the pres context is going away.
-   */
-  void Disconnect();
-
   /**
    * StyleContextChanged 
    *
@@ -83,7 +82,7 @@ public:
                         nsStyleContext *aNewStyleContext);
 
   // nsISupports
-  NS_DECL_ISUPPORTS
+  NS_DECL_ISUPPORTS_INHERITED
 
   // nsIStyleRuleProcessor
   NS_IMETHOD RulesMatching(ElementRuleProcessorData* aData);
@@ -121,7 +120,7 @@ private:
 			      nsCSSPseudoElements::Type aPseudoType);
 
   PRCList mElementTransitions;
-  nsPresContext *mPresContext; // weak (non-null from ctor to Disconnect)
+  nsPresContext *mPresContext;
 };
 
 #endif /* !defined(nsTransitionManager_h_) */
diff --git a/layout/style/test/Makefile.in b/layout/style/test/Makefile.in
index fcad0b9cfc5e..6734f9acae1d 100644
--- a/layout/style/test/Makefile.in
+++ b/layout/style/test/Makefile.in
@@ -138,7 +138,6 @@ _TEST_FILES =	test_acid3_test46.html \
 		test_system_font_serialization.html \
 		test_transitions_computed_values.html \
 		test_transitions_computed_value_combinations.html \
-		test_transitions_events.html \
 		test_transitions.html \
 		test_transitions_per_property.html \
 		test_transitions_dynamic_changes.html \
diff --git a/layout/style/test/test_transitions_events.html b/layout/style/test/test_transitions_events.html
deleted file mode 100644
index fc306f5ad891..000000000000
--- a/layout/style/test/test_transitions_events.html
+++ /dev/null
@@ -1,239 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=531585
--->
-<head>
-  <title>Test for Bug 531585 (transitionend event)</title>
-  <script type="application/javascript" src="/MochiKit/packed.js"></script>
-  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
-</head>
-<style type="text/css">
-
-.bar { margin: 10px; }
-
-#one { -moz-transition-duration: 500ms; -moz-transition-property: all; }
-#two { -moz-transition: margin-left 1s; }
-#three { -moz-transition: margin 0.5s 0.25s; }
-
-#four, #five, #six {
-  -moz-transition: 500ms color;
-  border-color: black; /* don't derive from color */
-}
-
-</style>
-<body>
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=531585">Mozilla Bug 531585</a>
-<p id="display">
-
-<span id="one" style="color:blue"></span>
-<span id="two"></span>
-<span id="three"></span>
-<span id="four" style="color: blue"></span>
-<span id="five" style="color: blue"></span>
-<span id="six" style="color: blue"></span>
-
-</p>
-<pre id="test">
-<script type="application/javascript">
-
-/** Test for Bug 531585 (transitionend event) **/
-
-SimpleTest.waitForExplicitFinish();
-var gTestCount = 0;
-function started_test() { ++gTestCount; }
-function finished_test() { if (--gTestCount == 0) { SimpleTest.finish(); } }
-
-function $(id) { return document.getElementById(id); }
-function cs(id) { return getComputedStyle($(id), ""); }
-
-var got_one_root = false;
-var got_one_target = false;
-var got_one_target_bordertop = false;
-var got_one_target_borderright = false;
-var got_one_target_borderbottom = false;
-var got_one_target_borderleft = false;
-var got_two_target = false;
-var got_three_top = false;
-var got_three_right = false;
-var got_three_bottom = false;
-var got_three_left = false;
-var got_four_root = false;
-var got_body = false;
-
-document.documentElement.addEventListener("transitionend",
-  function(event) {
-    if (event.target == $("one")) {
-      ok(!got_one_root, "transitionend on one on root");
-      is(event.propertyName, "border-right-color",
-         "propertyName for transitionend on one");
-      is(event.elapsedTime, 0.5,
-         "elapsedTime for transitionend on one");
-      is(cs("one").borderRightColor, "rgb(0, 255, 0)",
-         "computed style for transitionend on one");
-      got_one_root = true;
-      finished_test();
-    } else if (event.target == $("four")) {
-      ok(!got_four_root, "transitionend on four on root");
-      is(event.propertyName, "color",
-         "propertyName for transitionend on four");
-      // Reported time should (really?) be shortened by reversing.
-      ok(event.elapsedTime < 0.5,
-         "elapsedTime for transitionend on four");
-      is(cs("four").color, "rgb(0, 0, 255)",
-         "computed style for transitionend on four (end of reverse transition)");
-      got_four_root = true;
-      finished_test();
-    } else if (event.target == document.body) {
-      // A synthesized event.
-      ok(!got_body, "transitionend on body on root");
-      is(event.propertyName, "some-unknown-prop",
-         "propertyName for transitionend on body");
-      // Reported time should (really?) be shortened by reversing.
-      is(event.elapsedTime, -4.75,
-         "elapsedTime for transitionend on body");
-      got_body = true;
-      finished_test();
-    } else {
-      ok(false, "unexpected event");
-    }
-  }, false);
-
-$("one").addEventListener("transitionend",
-  function(event) {
-    switch (event.propertyName) {
-      case "color":
-        ok(!got_one_target, "transitionend on one on target");
-        got_one_target = true;
-        event.stopPropagation();
-        break;
-      case "border-top-color":
-        ok(!got_one_target_bordertop, "transitionend on one on target");
-        got_one_target_bordertop = true;
-        event.stopPropagation();
-        break;
-      case "border-right-color":
-        ok(!got_one_target_borderright, "transitionend on one on target");
-        got_one_target_borderright = true;
-        // Let this event through to body
-        break;
-      case "border-bottom-color":
-        ok(!got_one_target_borderbottom, "transitionend on one on target");
-        got_one_target_borderbottom = true;
-        event.stopPropagation();
-        break;
-      case "border-left-color":
-        ok(!got_one_target_borderleft, "transitionend on one on target");
-        got_one_target_borderleft = true;
-        event.stopPropagation();
-        break;
-      default:
-        ok(false, "unexpected property name " + event.propertyName +
-                  " for transitionend on one on target");
-    }
-    is(event.elapsedTime, 0.5,
-       "elapsedTime for transitionend on one");
-    is(cs("one").getPropertyValue(event.propertyName), "rgb(0, 255, 0)",
-       "computed style of " + event.propertyName + " for transitionend on one");
-    got_one_target = true;
-    finished_test();
-  }, false);
-
-started_test();
-started_test();
-started_test();
-started_test();
-started_test();
-started_test();
-$("one").style.color = "lime";
-
-
-$("two").addEventListener("transitionend",
-  function(event) {
-    event.stopPropagation();
-
-    ok(!got_two_target, "transitionend on two on target");
-    is(event.propertyName, "margin-left",
-       "propertyName for transitionend on two");
-    is(event.elapsedTime, 1,
-       "elapsedTime for transitionend on two");
-    is(cs("two").marginLeft, "10px",
-       "computed style for transitionend on two");
-    got_two_target = true;
-    finished_test();
-  }, false);
-
-started_test();
-$("two").className = "bar";
-
-$("three").addEventListener("transitionend",
-  function(event) {
-    event.stopPropagation();
-
-    switch (event.propertyName) {
-      case "margin-top":
-        ok(!got_three_top, "should only get margin-top once");
-        got_three_top = true;
-        break;
-      case "margin-right":
-        ok(!got_three_right, "should only get margin-right once");
-        got_three_right = true;
-        break;
-      case "margin-bottom":
-        ok(!got_three_bottom, "should only get margin-bottom once");
-        got_three_bottom = true;
-        break;
-      case "margin-left":
-        ok(!got_three_left, "should only get margin-left once");
-        got_three_left = true;
-        break;
-      default:
-        ok(false, "unexpected property name " + event.propertyName +
-                  " for transitionend on three");
-    }
-    is(event.elapsedTime, 0.5,
-       "elapsedTime for transitionend on three");
-    is(cs("three").getPropertyValue(event.propertyName), "10px",
-       "computed style for transitionend on three");
-    finished_test();
-  }, true);
-
-started_test();
-started_test();
-started_test();
-started_test();
-$("three").className = "bar";
-
-// We reverse the transition on four, and we should only get an event
-// at the end of the second transition.
-started_test();
-$("four").style.color = "lime";
-
-// We cancel the transition on five by changing 'transition-property',
-// and should thus get no event.
-$("five").style.color = "lime";
-
-// We cancel the transition on six by changing 'transition-duration' and
-// then changing the value, so we should get no event.
-$("six").style.color = "lime";
-
-setTimeout(function() {
-             $("four").style.color = "blue";
-             $("five").style.MozTransitionProperty = "margin-left";
-             $("six").style.MozTransitionDuration = "0s";
-             $("six").style.MozTransitionDelay = "0s";
-             $("six").style.color = "blue";
-           }, 100);
-
-// And make our own event to dispatch to the body.
-started_test();
-var ev = document.createEvent("TransitionEvent"); // FIXME: un-specified
-ev.initTransitionEvent("transitionend", true, true,
-                       "some-unknown-prop", -4.75);
-document.body.dispatchEvent(ev);
-
-</script>
-</pre>
-</body>
-</html>
diff --git a/widget/public/nsGUIEvent.h b/widget/public/nsGUIEvent.h
index 62392f3d15ce..db73ebe72a7a 100644
--- a/widget/public/nsGUIEvent.h
+++ b/widget/public/nsGUIEvent.h
@@ -91,7 +91,7 @@ class nsHashKey;
 #define NS_POPUP_EVENT                    23
 #define NS_COMMAND_EVENT                  24
 #define NS_SCROLLAREA_EVENT               25
-#define NS_TRANSITION_EVENT               26
+
 
 #define NS_UI_EVENT                       27
 #ifdef MOZ_SVG
@@ -448,8 +448,6 @@ class nsHashKey;
 #define NS_SCROLLAREA_EVENT_START    4100
 #define NS_SCROLLEDAREACHANGED       (NS_SCROLLAREA_EVENT_START)
 
-#define NS_TRANSITION_EVENT_START    4200
-#define NS_TRANSITION_END            (NS_TRANSITION_EVENT_START)
 
 /**
  * Return status for event processors, nsEventStatus, is defined in
@@ -1331,21 +1329,6 @@ public:
   PRFloat64 delta;      // Delta for magnify and rotate events
 };
 
-class nsTransitionEvent : public nsEvent
-{
-public:
-  nsTransitionEvent(PRBool isTrusted, PRUint32 msg,
-                    const nsString &propertyNameArg, float elapsedTimeArg)
-    : nsEvent(isTrusted, msg, NS_TRANSITION_EVENT),
-      propertyName(propertyNameArg), elapsedTime(elapsedTimeArg)
-  {
-  }
-
-  nsString propertyName;
-  float elapsedTime;
-};
-
-
 /**
  * Event status for D&D Event
  */