--- a/dom/bindings/Bindings.conf
+++ b/dom/bindings/Bindings.conf
@@ -812,20 +812,16 @@ DOMInterfaces = {
 'MozTimeManager': {
     'nativeType': 'mozilla::dom::time::TimeManager',
 },
 
 'MozVoicemail': {
     'nativeType': 'mozilla::dom::Voicemail',
 },
 
-'MutationEvent': {
-    'nativeType': 'nsDOMMutationEvent',
-},
-
 'MutationObserver': {
     'nativeType': 'nsDOMMutationObserver',
 },
 
 'MutationRecord': {
     'nativeType': 'nsDOMMutationRecord',
     'headerFile': 'nsDOMMutationObserver.h',
     'resultNotAddRefed': [ 'target', 'addedNodes', 'removedNodes',

rename from dom/events/nsDOMMutationEvent.cpp
rename to dom/events/MutationEvent.cpp
--- a/dom/events/nsDOMMutationEvent.cpp
+++ b/dom/events/MutationEvent.cpp
@@ -1,96 +1,104 @@
 /* -*- Mode: C++; 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 "nsCOMPtr.h"
-#include "nsDOMMutationEvent.h"
+#include "mozilla/dom/MutationEvent.h"
 #include "mozilla/InternalMutationEvent.h"
 
-using namespace mozilla;
-
 class nsPresContext;
 
-nsDOMMutationEvent::nsDOMMutationEvent(mozilla::dom::EventTarget* aOwner,
-                                       nsPresContext* aPresContext,
-                                       InternalMutationEvent* aEvent)
+namespace mozilla {
+namespace dom {
+
+MutationEvent::MutationEvent(EventTarget* aOwner,
+                             nsPresContext* aPresContext,
+                             InternalMutationEvent* aEvent)
   : nsDOMEvent(aOwner, aPresContext,
                aEvent ? aEvent : new InternalMutationEvent(false, 0))
 {
   mEventIsInternal = (aEvent == nullptr);
 }
 
-NS_INTERFACE_MAP_BEGIN(nsDOMMutationEvent)
+NS_INTERFACE_MAP_BEGIN(MutationEvent)
   NS_INTERFACE_MAP_ENTRY(nsIDOMMutationEvent)
 NS_INTERFACE_MAP_END_INHERITING(nsDOMEvent)
 
-NS_IMPL_ADDREF_INHERITED(nsDOMMutationEvent, nsDOMEvent)
-NS_IMPL_RELEASE_INHERITED(nsDOMMutationEvent, nsDOMEvent)
+NS_IMPL_ADDREF_INHERITED(MutationEvent, nsDOMEvent)
+NS_IMPL_RELEASE_INHERITED(MutationEvent, nsDOMEvent)
 
 already_AddRefed<nsINode>
-nsDOMMutationEvent::GetRelatedNode()
+MutationEvent::GetRelatedNode()
 {
   nsCOMPtr<nsINode> n =
     do_QueryInterface(mEvent->AsMutationEvent()->mRelatedNode);
   return n.forget();
 }
 
 NS_IMETHODIMP
-nsDOMMutationEvent::GetRelatedNode(nsIDOMNode** aRelatedNode)
+MutationEvent::GetRelatedNode(nsIDOMNode** aRelatedNode)
 {
   nsCOMPtr<nsINode> relatedNode = GetRelatedNode();
   nsCOMPtr<nsIDOMNode> relatedDOMNode = relatedNode ? relatedNode->AsDOMNode() : nullptr;
   relatedDOMNode.forget(aRelatedNode);
   return NS_OK;
 }
 
 NS_IMETHODIMP
-nsDOMMutationEvent::GetPrevValue(nsAString& aPrevValue)
+MutationEvent::GetPrevValue(nsAString& aPrevValue)
 {
   InternalMutationEvent* mutation = mEvent->AsMutationEvent();
   if (mutation->mPrevAttrValue)
     mutation->mPrevAttrValue->ToString(aPrevValue);
   return NS_OK;
 }
 
 NS_IMETHODIMP
-nsDOMMutationEvent::GetNewValue(nsAString& aNewValue)
+MutationEvent::GetNewValue(nsAString& aNewValue)
 {
   InternalMutationEvent* mutation = mEvent->AsMutationEvent();
   if (mutation->mNewAttrValue)
       mutation->mNewAttrValue->ToString(aNewValue);
   return NS_OK;
 }
 
 NS_IMETHODIMP
-nsDOMMutationEvent::GetAttrName(nsAString& aAttrName)
+MutationEvent::GetAttrName(nsAString& aAttrName)
 {
   InternalMutationEvent* mutation = mEvent->AsMutationEvent();
   if (mutation->mAttrName)
       mutation->mAttrName->ToString(aAttrName);
   return NS_OK;
 }
 
 uint16_t
-nsDOMMutationEvent::AttrChange()
+MutationEvent::AttrChange()
 {
   return mEvent->AsMutationEvent()->mAttrChange;
 }
 
 NS_IMETHODIMP
-nsDOMMutationEvent::GetAttrChange(uint16_t* aAttrChange)
+MutationEvent::GetAttrChange(uint16_t* aAttrChange)
 {
   *aAttrChange = AttrChange();
   return NS_OK;
 }
 
 NS_IMETHODIMP
-nsDOMMutationEvent::InitMutationEvent(const nsAString& aTypeArg, bool aCanBubbleArg, bool aCancelableArg, nsIDOMNode* aRelatedNodeArg, const nsAString& aPrevValueArg, const nsAString& aNewValueArg, const nsAString& aAttrNameArg, uint16_t aAttrChangeArg)
+MutationEvent::InitMutationEvent(const nsAString& aTypeArg,
+                                 bool aCanBubbleArg,
+                                 bool aCancelableArg,
+                                 nsIDOMNode* aRelatedNodeArg,
+                                 const nsAString& aPrevValueArg,
+                                 const nsAString& aNewValueArg,
+                                 const nsAString& aAttrNameArg,
+                                 uint16_t aAttrChangeArg)
 {
   nsresult rv = nsDOMEvent::InitEvent(aTypeArg, aCanBubbleArg, aCancelableArg);
   NS_ENSURE_SUCCESS(rv, rv);
 
   InternalMutationEvent* mutation = mEvent->AsMutationEvent();
   mutation->mRelatedNode = aRelatedNodeArg;
   if (!aPrevValueArg.IsEmpty())
     mutation->mPrevAttrValue = do_GetAtom(aPrevValueArg);
@@ -99,17 +107,23 @@ nsDOMMutationEvent::InitMutationEvent(co
   if (!aAttrNameArg.IsEmpty()) {
     mutation->mAttrName = do_GetAtom(aAttrNameArg);
   }
   mutation->mAttrChange = aAttrChangeArg;
     
   return NS_OK;
 }
 
-nsresult NS_NewDOMMutationEvent(nsIDOMEvent** aInstancePtrResult,
-                                mozilla::dom::EventTarget* aOwner,
-                                nsPresContext* aPresContext,
-                                InternalMutationEvent* aEvent) 
+} // namespace dom
+} // namespace mozilla
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+nsresult
+NS_NewDOMMutationEvent(nsIDOMEvent** aInstancePtrResult,
+                       EventTarget* aOwner,
+                       nsPresContext* aPresContext,
+                       InternalMutationEvent* aEvent) 
 {
-  nsDOMMutationEvent* it = new nsDOMMutationEvent(aOwner, aPresContext, aEvent);
-
+  MutationEvent* it = new MutationEvent(aOwner, aPresContext, aEvent);
   return CallQueryInterface(it, aInstancePtrResult);
 }

rename from dom/events/nsDOMMutationEvent.h
rename to dom/events/MutationEvent.h
--- a/dom/events/nsDOMMutationEvent.h
+++ b/dom/events/MutationEvent.h
@@ -1,41 +1,44 @@
 /* -*- Mode: C++; 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/. */
 
-#ifndef nsDOMMutationEvent_h__
-#define nsDOMMutationEvent_h__
+#ifndef mozilla_dom_MutationEvent_h_
+#define mozilla_dom_MutationEvent_h_
 
 #include "nsIDOMMutationEvent.h"
 #include "nsINode.h"
 #include "nsDOMEvent.h"
 #include "mozilla/dom/MutationEventBinding.h"
 #include "mozilla/EventForwards.h"
 
-class nsDOMMutationEvent : public nsDOMEvent,
-                           public nsIDOMMutationEvent
+namespace mozilla {
+namespace dom {
+
+class MutationEvent : public nsDOMEvent,
+                      public nsIDOMMutationEvent
 {
 public:
-  nsDOMMutationEvent(mozilla::dom::EventTarget* aOwner,
-                     nsPresContext* aPresContext,
-                     mozilla::InternalMutationEvent* aEvent);
+  MutationEvent(EventTarget* aOwner,
+                nsPresContext* aPresContext,
+                InternalMutationEvent* aEvent);
 
   NS_DECL_ISUPPORTS_INHERITED
 
   NS_DECL_NSIDOMMUTATIONEVENT
 
   // Forward to base class
   NS_FORWARD_TO_NSDOMEVENT
 
   virtual JSObject* WrapObject(JSContext* aCx,
                                JS::Handle<JSObject*> aScope) MOZ_OVERRIDE
   {
-    return mozilla::dom::MutationEventBinding::Wrap(aCx, aScope, this);
+    return MutationEventBinding::Wrap(aCx, aScope, this);
   }
 
   // xpidl implementation
   // GetPrevValue(nsAString& aPrevValue);
   // GetNewValue(nsAString& aNewValue);
   // GetAttrName(nsAString& aAttrName);
 
   already_AddRefed<nsINode> GetRelatedNode();
@@ -43,17 +46,20 @@ public:
   uint16_t AttrChange();
 
   void InitMutationEvent(const nsAString& aType,
                          bool& aCanBubble, bool& aCancelable,
                          nsINode* aRelatedNode,
                          const nsAString& aPrevValue,
                          const nsAString& aNewValue,
                          const nsAString& aAttrName,
-                         uint16_t& aAttrChange, mozilla::ErrorResult& aRv)
+                         uint16_t& aAttrChange, ErrorResult& aRv)
   {
     aRv = InitMutationEvent(aType, aCanBubble, aCancelable,
                             aRelatedNode ? aRelatedNode->AsDOMNode() : nullptr,
                             aPrevValue, aNewValue, aAttrName, aAttrChange);
   }
 };
 
-#endif // nsDOMMutationEvent_h__
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_MutationEvent_h_

--- a/dom/events/moz.build
+++ b/dom/events/moz.build
@@ -46,16 +46,17 @@ EXPORTS.mozilla.dom += [
     'DeviceMotionEvent.h',
     'DragEvent.h',
     'EventTarget.h',
     'FocusEvent.h',
     'KeyboardEvent.h',
     'MessageEvent.h',
     'MouseEvent.h',
     'MouseScrollEvent.h',
+    'MutationEvent.h',
     'PointerEvent.h',
     'SimpleGestureEvent.h',
     'Touch.h',
     'WheelEvent.h',
 ]
 
 if CONFIG['MOZ_WEBSPEECH']:
     EXPORTS.mozilla.dom += ['SpeechRecognitionError.h']
@@ -71,20 +72,20 @@ UNIFIED_SOURCES += [
     'DeviceMotionEvent.cpp',
     'DragEvent.cpp',
     'EventTarget.cpp',
     'FocusEvent.cpp',
     'KeyboardEvent.cpp',
     'MessageEvent.cpp',
     'MouseEvent.cpp',
     'MouseScrollEvent.cpp',
+    'MutationEvent.cpp',
     'nsAsyncDOMEvent.cpp',
     'nsContentEventHandler.cpp',
     'nsDOMEventTargetHelper.cpp',
-    'nsDOMMutationEvent.cpp',
     'nsDOMNotifyAudioAvailableEvent.cpp',
     'nsDOMTextEvent.cpp',
     'nsDOMTouchEvent.cpp',
     'nsDOMTransitionEvent.cpp',
     'nsDOMXULCommandEvent.cpp',
     'nsEventDispatcher.cpp',
     'nsEventListenerService.cpp',
     'nsIMEStateManager.cpp',