diff --git a/content/svg/content/src/SVGAnimatedLength.cpp b/content/svg/content/src/SVGAnimatedLength.cpp
index f1036007bda8..255786d9ee78 100644
--- a/content/svg/content/src/SVGAnimatedLength.cpp
+++ b/content/svg/content/src/SVGAnimatedLength.cpp
@@ -18,7 +18,6 @@ NS_IMPL_CYCLE_COLLECTING_RELEASE(SVGAnimatedLength)
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(SVGAnimatedLength)
   NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
-  NS_INTERFACE_MAP_ENTRY(nsIDOMSVGAnimatedLength)
   NS_INTERFACE_MAP_ENTRY(nsISupports)
 NS_INTERFACE_MAP_END
 
diff --git a/content/svg/content/src/SVGAnimatedLength.h b/content/svg/content/src/SVGAnimatedLength.h
index 54a92f6e521d..b38ff7e4fb9e 100644
--- a/content/svg/content/src/SVGAnimatedLength.h
+++ b/content/svg/content/src/SVGAnimatedLength.h
@@ -8,7 +8,6 @@
 
 #include "mozilla/Attributes.h"
 #include "nsSVGElement.h"
-#include "nsIDOMSVGAnimatedLength.h"
 
 class nsSVGLength2;
 class nsIDOMSVGLength;
@@ -16,7 +15,7 @@ class nsIDOMSVGLength;
 namespace mozilla {
 namespace dom {
 
-class SVGAnimatedLength MOZ_FINAL : public nsIDOMSVGAnimatedLength,
+class SVGAnimatedLength MOZ_FINAL : public nsISupports,
                                     public nsWrapperCache
 {
 public:
@@ -29,12 +28,6 @@ public:
 
   ~SVGAnimatedLength();
 
-  NS_IMETHOD GetBaseVal(nsIDOMSVGLength **aBaseVal) MOZ_OVERRIDE
-    { *aBaseVal = BaseVal().get(); return NS_OK; }
-
-  NS_IMETHOD GetAnimVal(nsIDOMSVGLength **aAnimVal) MOZ_OVERRIDE
-    { *aAnimVal = AnimVal().get(); return NS_OK; }
-
   // WebIDL
   nsSVGElement* GetParentObject() { return mSVGElement; }
   virtual JSObject* WrapObject(JSContext* aCx,
diff --git a/content/svg/content/src/SVGTextContentElement.cpp b/content/svg/content/src/SVGTextContentElement.cpp
index a0a5de1c6b22..cabedb1528a7 100644
--- a/content/svg/content/src/SVGTextContentElement.cpp
+++ b/content/svg/content/src/SVGTextContentElement.cpp
@@ -7,7 +7,6 @@
 #include "nsISVGPoint.h"
 #include "nsSVGTextContainerFrame.h"
 #include "nsSVGTextFrame2.h"
-#include "nsIDOMSVGAnimatedLength.h"
 #include "mozilla/dom/SVGIRect.h"
 #include "nsIDOMSVGAnimatedEnum.h"
 
diff --git a/content/svg/content/src/nsSVGLength2.cpp b/content/svg/content/src/nsSVGLength2.cpp
index 6e5b3322e830..72ae4b49da31 100644
--- a/content/svg/content/src/nsSVGLength2.cpp
+++ b/content/svg/content/src/nsSVGLength2.cpp
@@ -471,14 +471,6 @@ nsSVGLength2::SetAnimValue(float aValue, nsSVGElement *aSVGElement)
                                aSVGElement);
 }
 
-nsresult
-nsSVGLength2::ToDOMAnimatedLength(nsIDOMSVGAnimatedLength **aResult,
-                                  nsSVGElement *aSVGElement)
-{
-  *aResult = ToDOMAnimatedLength(aSVGElement).get();
-  return NS_OK;
-}
-
 already_AddRefed<SVGAnimatedLength>
 nsSVGLength2::ToDOMAnimatedLength(nsSVGElement* aSVGElement)
 {
diff --git a/content/svg/content/src/nsSVGLength2.h b/content/svg/content/src/nsSVGLength2.h
index 5c9f182da992..4e5ca0103439 100644
--- a/content/svg/content/src/nsSVGLength2.h
+++ b/content/svg/content/src/nsSVGLength2.h
@@ -11,7 +11,6 @@
 #include "nsCoord.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsError.h"
-#include "nsIDOMSVGAnimatedLength.h"
 #include "nsIDOMSVGLength.h"
 #include "nsISMILAttr.h"
 #include "nsMathUtils.h"
@@ -89,9 +88,6 @@ public:
   // useable, and represents the default base value of the attribute.
   bool IsExplicitlySet() const
     { return mIsAnimated || mIsBaseSet; }
-  
-  nsresult ToDOMAnimatedLength(nsIDOMSVGAnimatedLength **aResult,
-                               nsSVGElement* aSVGElement);
 
   already_AddRefed<mozilla::dom::SVGAnimatedLength>
   ToDOMAnimatedLength(nsSVGElement* aSVGElement);
diff --git a/dom/interfaces/svg/moz.build b/dom/interfaces/svg/moz.build
index b3808823edcb..b41c9da28422 100644
--- a/dom/interfaces/svg/moz.build
+++ b/dom/interfaces/svg/moz.build
@@ -7,7 +7,6 @@
 XPIDL_SOURCES += [
     'nsIDOMSVGAnimatedEnum.idl',
     'nsIDOMSVGAnimatedInteger.idl',
-    'nsIDOMSVGAnimatedLength.idl',
     'nsIDOMSVGAnimatedNumber.idl',
     'nsIDOMSVGElement.idl',
     'nsIDOMSVGLength.idl',
diff --git a/dom/interfaces/svg/nsIDOMSVGAnimatedLength.idl b/dom/interfaces/svg/nsIDOMSVGAnimatedLength.idl
deleted file mode 100644
index feddde808d8c..000000000000
--- a/dom/interfaces/svg/nsIDOMSVGAnimatedLength.idl
+++ /dev/null
@@ -1,16 +0,0 @@
-/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* 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/. */
-
-#include "domstubs.idl"
-
-interface nsIDOMSVGLength;
-
-[scriptable, uuid(a52f0322-7f4d-418d-af6d-a7b14abd5cdf)]
-interface nsIDOMSVGAnimatedLength : nsISupports
-{
-  readonly attribute nsIDOMSVGLength baseVal;
-  readonly attribute nsIDOMSVGLength animVal;
-};
-
diff --git a/image/src/SVGDocumentWrapper.cpp b/image/src/SVGDocumentWrapper.cpp
index 2bbd67822df7..908d0d002de8 100644
--- a/image/src/SVGDocumentWrapper.cpp
+++ b/image/src/SVGDocumentWrapper.cpp
@@ -12,7 +12,6 @@
 #include "nsIContentViewer.h"
 #include "nsIDocument.h"
 #include "nsIDocumentLoaderFactory.h"
-#include "nsIDOMSVGAnimatedLength.h"
 #include "nsIDOMSVGLength.h"
 #include "nsIHttpChannel.h"
 #include "nsIObserverService.h"
@@ -86,14 +85,12 @@ SVGDocumentWrapper::GetWidthOrHeight(Dimension aDimension,
   NS_ENSURE_TRUE(domAnimLength, false);
 
   // Get the animated value from the object
-  nsRefPtr<nsIDOMSVGLength> domLength;
-  nsresult rv = domAnimLength->GetAnimVal(getter_AddRefs(domLength));
-  NS_ENSURE_SUCCESS(rv, false);
+  nsRefPtr<nsIDOMSVGLength> domLength = domAnimLength->AnimVal();
   NS_ENSURE_TRUE(domLength, false);
 
   // Check if it's a percent value (and fail if so)
   uint16_t unitType;
-  rv = domLength->GetUnitType(&unitType);
+  nsresult rv = domLength->GetUnitType(&unitType);
   NS_ENSURE_SUCCESS(rv, false);
   if (unitType == nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE) {
     return false;