diff --git a/dom/bindings/Bindings.conf b/dom/bindings/Bindings.conf
index 0953eef05bf1..fc704fa30c93 100644
--- a/dom/bindings/Bindings.conf
+++ b/dom/bindings/Bindings.conf
@@ -1231,10 +1231,6 @@ DOMInterfaces = {
     'headerFile': 'mozilla/dom/TouchEvent.h',
 },
 
-'TransitionEvent': {
-    'nativeType': 'nsDOMTransitionEvent',
-},
-
 'TreeColumns': {
     'nativeType': 'nsTreeColumns',
 },
diff --git a/dom/events/nsDOMTransitionEvent.cpp b/dom/events/TransitionEvent.cpp
similarity index 52%
rename from dom/events/nsDOMTransitionEvent.cpp
rename to dom/events/TransitionEvent.cpp
index b2722d38e5aa..dc016d633faf 100644
--- a/dom/events/nsDOMTransitionEvent.cpp
+++ b/dom/events/TransitionEvent.cpp
@@ -3,15 +3,16 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "nsDOMTransitionEvent.h"
-#include "prtime.h"
+#include "mozilla/dom/TransitionEvent.h"
 #include "mozilla/ContentEvents.h"
+#include "prtime.h"
 
-using namespace mozilla;
+namespace mozilla {
+namespace dom {
 
-nsDOMTransitionEvent::nsDOMTransitionEvent(mozilla::dom::EventTarget* aOwner,
-                                           nsPresContext *aPresContext,
-                                           InternalTransitionEvent* aEvent)
+TransitionEvent::TransitionEvent(EventTarget* aOwner,
+                                 nsPresContext* aPresContext,
+                                 InternalTransitionEvent* aEvent)
   : nsDOMEvent(aOwner, aPresContext,
                aEvent ? aEvent : new InternalTransitionEvent(false, 0))
 {
@@ -24,22 +25,22 @@ nsDOMTransitionEvent::nsDOMTransitionEvent(mozilla::dom::EventTarget* aOwner,
   }
 }
 
-NS_INTERFACE_MAP_BEGIN(nsDOMTransitionEvent)
+NS_INTERFACE_MAP_BEGIN(TransitionEvent)
   NS_INTERFACE_MAP_ENTRY(nsIDOMTransitionEvent)
 NS_INTERFACE_MAP_END_INHERITING(nsDOMEvent)
 
-NS_IMPL_ADDREF_INHERITED(nsDOMTransitionEvent, nsDOMEvent)
-NS_IMPL_RELEASE_INHERITED(nsDOMTransitionEvent, nsDOMEvent)
+NS_IMPL_ADDREF_INHERITED(TransitionEvent, nsDOMEvent)
+NS_IMPL_RELEASE_INHERITED(TransitionEvent, nsDOMEvent)
 
-//static
-already_AddRefed<nsDOMTransitionEvent>
-nsDOMTransitionEvent::Constructor(const mozilla::dom::GlobalObject& aGlobal,
-                                  const nsAString& aType,
-                                  const mozilla::dom::TransitionEventInit& aParam,
-                                  mozilla::ErrorResult& aRv)
+// static
+already_AddRefed<TransitionEvent>
+TransitionEvent::Constructor(const GlobalObject& aGlobal,
+                             const nsAString& aType,
+                             const TransitionEventInit& aParam,
+                             ErrorResult& aRv)
 {
-  nsCOMPtr<mozilla::dom::EventTarget> t = do_QueryInterface(aGlobal.GetAsSupports());
-  nsRefPtr<nsDOMTransitionEvent> e = new nsDOMTransitionEvent(t, nullptr, nullptr);
+  nsCOMPtr<EventTarget> t = do_QueryInterface(aGlobal.GetAsSupports());
+  nsRefPtr<TransitionEvent> e = new TransitionEvent(t, nullptr, nullptr);
   bool trusted = e->Init(t);
 
   aRv = e->InitEvent(aType, aParam.mBubbles, aParam.mCancelable);
@@ -54,39 +55,44 @@ nsDOMTransitionEvent::Constructor(const mozilla::dom::GlobalObject& aGlobal,
 }
 
 NS_IMETHODIMP
-nsDOMTransitionEvent::GetPropertyName(nsAString & aPropertyName)
+TransitionEvent::GetPropertyName(nsAString& aPropertyName)
 {
   aPropertyName = mEvent->AsTransitionEvent()->propertyName;
   return NS_OK;
 }
 
 NS_IMETHODIMP
-nsDOMTransitionEvent::GetElapsedTime(float *aElapsedTime)
+TransitionEvent::GetElapsedTime(float* aElapsedTime)
 {
   *aElapsedTime = ElapsedTime();
   return NS_OK;
 }
 
 float
-nsDOMTransitionEvent::ElapsedTime()
+TransitionEvent::ElapsedTime()
 {
   return mEvent->AsTransitionEvent()->elapsedTime;
 }
 
 NS_IMETHODIMP
-nsDOMTransitionEvent::GetPseudoElement(nsAString& aPseudoElement)
+TransitionEvent::GetPseudoElement(nsAString& aPseudoElement)
 {
   aPseudoElement = mEvent->AsTransitionEvent()->pseudoElement;
   return NS_OK;
 }
 
+} // namespace dom
+} // namespace mozilla
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
 nsresult
-NS_NewDOMTransitionEvent(nsIDOMEvent **aInstancePtrResult,
-                         mozilla::dom::EventTarget* aOwner,
-                         nsPresContext *aPresContext,
+NS_NewDOMTransitionEvent(nsIDOMEvent** aInstancePtrResult,
+                         EventTarget* aOwner,
+                         nsPresContext* aPresContext,
                          InternalTransitionEvent* aEvent)
 {
-  nsDOMTransitionEvent *it =
-    new nsDOMTransitionEvent(aOwner, aPresContext, aEvent);
+  TransitionEvent *it = new TransitionEvent(aOwner, aPresContext, aEvent);
   return CallQueryInterface(it, aInstancePtrResult);
 }
diff --git a/dom/events/nsDOMTransitionEvent.h b/dom/events/TransitionEvent.h
similarity index 51%
rename from dom/events/nsDOMTransitionEvent.h
rename to dom/events/TransitionEvent.h
index ee243c12a3d9..5bab83b8e05d 100644
--- a/dom/events/nsDOMTransitionEvent.h
+++ b/dom/events/TransitionEvent.h
@@ -2,8 +2,8 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-#ifndef nsDOMTransitionEvent_h_
-#define nsDOMTransitionEvent_h_
+#ifndef mozilla_dom_TransitionEvent_h_
+#define mozilla_dom_TransitionEvent_h_
 
 #include "nsDOMEvent.h"
 #include "nsIDOMTransitionEvent.h"
@@ -12,28 +12,31 @@
 
 class nsAString;
 
-class nsDOMTransitionEvent : public nsDOMEvent,
-                             public nsIDOMTransitionEvent
+namespace mozilla {
+namespace dom {
+
+class TransitionEvent : public nsDOMEvent,
+                        public nsIDOMTransitionEvent
 {
 public:
-  nsDOMTransitionEvent(mozilla::dom::EventTarget* aOwner,
-                       nsPresContext *aPresContext,
-                       mozilla::InternalTransitionEvent* aEvent);
+  TransitionEvent(EventTarget* aOwner,
+                  nsPresContext* aPresContext,
+                  InternalTransitionEvent* aEvent);
 
   NS_DECL_ISUPPORTS_INHERITED
   NS_FORWARD_TO_NSDOMEVENT
   NS_DECL_NSIDOMTRANSITIONEVENT
 
-  static already_AddRefed<nsDOMTransitionEvent>
-  Constructor(const mozilla::dom::GlobalObject& aGlobal,
+  static already_AddRefed<TransitionEvent>
+  Constructor(const GlobalObject& aGlobal,
               const nsAString& aType,
-              const mozilla::dom::TransitionEventInit& aParam,
-              mozilla::ErrorResult& aRv);
+              const TransitionEventInit& aParam,
+              ErrorResult& aRv);
 
   virtual JSObject* WrapObject(JSContext* aCx,
-			       JS::Handle<JSObject*> aScope) MOZ_OVERRIDE
+                               JS::Handle<JSObject*> aScope) MOZ_OVERRIDE
   {
-    return mozilla::dom::TransitionEventBinding::Wrap(aCx, aScope, this);
+    return TransitionEventBinding::Wrap(aCx, aScope, this);
   }
 
   // xpidl implementation
@@ -43,4 +46,7 @@ public:
   float ElapsedTime();
 };
 
-#endif /* !defined(nsDOMTransitionEvent_h_) */
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TransitionEvent_h_
diff --git a/dom/events/moz.build b/dom/events/moz.build
index 5c0852fff715..11b9cc577314 100644
--- a/dom/events/moz.build
+++ b/dom/events/moz.build
@@ -56,6 +56,7 @@ EXPORTS.mozilla.dom += [
     'SimpleGestureEvent.h',
     'Touch.h',
     'TouchEvent.h',
+    'TransitionEvent.h',
     'WheelEvent.h',
 ]
 
@@ -84,7 +85,6 @@ UNIFIED_SOURCES += [
     'nsContentEventHandler.cpp',
     'nsDOMEventTargetHelper.cpp',
     'nsDOMTextEvent.cpp',
-    'nsDOMTransitionEvent.cpp',
     'nsDOMXULCommandEvent.cpp',
     'nsEventDispatcher.cpp',
     'nsEventListenerService.cpp',
@@ -97,6 +97,7 @@ UNIFIED_SOURCES += [
     'TextComposition.cpp',
     'Touch.cpp',
     'TouchEvent.cpp',
+    'TransitionEvent.cpp',
     'WheelEvent.cpp',
 ]