--- a/dom/events/EventListenerManager.cpp
+++ b/dom/events/EventListenerManager.cpp
@@ -110,16 +110,29 @@ IsWebkitPrefixSupportEnabled()
     sIsPrefCached = true;
     Preferences::AddBoolVarCache(&sIsWebkitPrefixSupportEnabled,
                                  "layout.css.prefixes.webkit");
   }
 
   return sIsWebkitPrefixSupportEnabled;
 }
 
+static bool
+IsPrefixedPointerLockEnabled()
+{
+  static bool sIsPrefixedPointerLockEnabled;
+  static bool sIsPrefCached = false;
+  if (!sIsPrefCached) {
+    sIsPrefCached = true;
+    Preferences::AddBoolVarCache(&sIsPrefixedPointerLockEnabled,
+                                 "pointer-lock-api.prefixed.enabled");
+  }
+  return sIsPrefixedPointerLockEnabled;
+}
+
 EventListenerManagerBase::EventListenerManagerBase()
   : mNoListenerForEvent(eVoidEvent)
   , mMayHavePaintEventListener(false)
   , mMayHaveMutationListeners(false)
   , mMayHaveCapturingListeners(false)
   , mMayHaveSystemGroupListeners(false)
   , mMayHaveTouchEventListener(false)
   , mMayHaveMouseEnterLeaveEventListener(false)
@@ -1123,41 +1136,47 @@ EventListenerManager::HandleEventSubType
   return result;
 }
 
 EventMessage
 EventListenerManager::GetLegacyEventMessage(EventMessage aEventMessage) const
 {
   // (If we're off-main-thread, we can't check the pref; so we just behave as
   // if it's disabled.)
-  if (mIsMainThreadELM && IsWebkitPrefixSupportEnabled()) {
-    // webkit-prefixed legacy events:
-    if (aEventMessage == eTransitionEnd) {
-      return eWebkitTransitionEnd;
+  if (mIsMainThreadELM) {
+    if (IsWebkitPrefixSupportEnabled()) {
+      // webkit-prefixed legacy events:
+      if (aEventMessage == eTransitionEnd) {
+        return eWebkitTransitionEnd;
+      }
+      if (aEventMessage == eAnimationStart) {
+        return eWebkitAnimationStart;
+      }
+      if (aEventMessage == eAnimationEnd) {
+        return eWebkitAnimationEnd;
+      }
+      if (aEventMessage == eAnimationIteration) {
+        return eWebkitAnimationIteration;
+      }
     }
-    if (aEventMessage == eAnimationStart) {
-      return eWebkitAnimationStart;
-    }
-    if (aEventMessage == eAnimationEnd) {
-      return eWebkitAnimationEnd;
-    }
-    if (aEventMessage == eAnimationIteration) {
-      return eWebkitAnimationIteration;
+    if (IsPrefixedPointerLockEnabled()) {
+      switch (aEventMessage) {
+        case ePointerLockChange:
+          return eMozPointerLockChange;
+        case ePointerLockError:
+          return eMozPointerLockError;
+      }
     }
   }
 
   switch (aEventMessage) {
     case eFullscreenChange:
       return eMozFullscreenChange;
     case eFullscreenError:
       return eMozFullscreenError;
-    case ePointerLockChange:
-      return eMozPointerLockChange;
-    case ePointerLockError:
-      return eMozPointerLockError;
     default:
       return aEventMessage;
   }
 }
 
 /**
 * Causes a check for event listeners and processing by them if they exist.
 * @param an event listener

--- a/dom/webidl/Document.webidl
+++ b/dom/webidl/Document.webidl
@@ -252,20 +252,20 @@ partial interface Document {
   [Func="nsDocument::IsUnprefixedFullscreenEnabled"]
   attribute EventHandler onfullscreenerror;
 };
 
 // https://w3c.github.io/pointerlock/#extensions-to-the-document-interface
 // https://w3c.github.io/pointerlock/#extensions-to-the-documentorshadowroot-mixin
 partial interface Document {
   readonly attribute Element? pointerLockElement;
-  [BinaryName="pointerLockElement"]
+  [BinaryName="pointerLockElement", Pref="pointer-lock-api.prefixed.enabled"]
   readonly attribute Element? mozPointerLockElement;
   void exitPointerLock();
-  [BinaryName="exitPointerLock"]
+  [BinaryName="exitPointerLock", Pref="pointer-lock-api.prefixed.enabled"]
   void mozExitPointerLock();
 
   // Event handlers
   attribute EventHandler onpointerlockchange;
   attribute EventHandler onpointerlockerror;
 };
 
 //http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/custom/index.html#dfn-document-register

--- a/dom/webidl/Element.webidl
+++ b/dom/webidl/Element.webidl
@@ -265,11 +265,11 @@ partial interface Element {
   [Throws, UnsafeInPrerendering, BinaryName="requestFullscreen"]
   void mozRequestFullScreen(optional any options);
 };
 
 // https://w3c.github.io/pointerlock/#extensions-to-the-element-interface
 partial interface Element {
   [UnsafeInPrerendering]
   void requestPointerLock();
-  [UnsafeInPrerendering, BinaryName="requestPointerLock"]
+  [UnsafeInPrerendering, BinaryName="requestPointerLock", Pref="pointer-lock-api.prefixed.enabled"]
   void mozRequestPointerLock();
 };

--- a/dom/webidl/EventHandler.webidl
+++ b/dom/webidl/EventHandler.webidl
@@ -116,17 +116,19 @@ interface GlobalEventHandlers {
            attribute EventHandler ongotpointercapture;
            [Pref="dom.w3c_pointer_events.enabled"]
            attribute EventHandler onlostpointercapture;
 
            // Mozilla-specific handlers. Unprefixed handlers live in
            // Document rather than here.
            attribute EventHandler onmozfullscreenchange;
            attribute EventHandler onmozfullscreenerror;
+           [Pref="pointer-lock-api.prefixed.enabled"]
            attribute EventHandler onmozpointerlockchange;
+           [Pref="pointer-lock-api.prefixed.enabled"]
            attribute EventHandler onmozpointerlockerror;
 };
 
 [NoInterfaceObject]
 interface WindowEventHandlers {
            attribute EventHandler onafterprint;
            attribute EventHandler onbeforeprint;
            attribute OnBeforeUnloadEventHandler onbeforeunload;

--- a/dom/webidl/MouseEvent.webidl
+++ b/dom/webidl/MouseEvent.webidl
@@ -66,19 +66,19 @@ dictionary MouseEventInit : EventModifie
   // Pointer Lock
   long           movementX = 0;
   long           movementY = 0;
 };
 
 // Mozilla extensions
 partial interface MouseEvent
 {
-  [BinaryName="movementX"]
+  [BinaryName="movementX", Pref="pointer-lock-api.prefixed.enabled"]
   readonly attribute long mozMovementX;
-  [BinaryName="movementY"]
+  [BinaryName="movementY", Pref="pointer-lock-api.prefixed.enabled"]
   readonly attribute long mozMovementY;
 
   // Finger or touch pressure event value
   // ranges between 0.0 and 1.0
   readonly attribute float mozPressure;
 
   const unsigned short    MOZ_SOURCE_UNKNOWN    = 0;
   const unsigned short    MOZ_SOURCE_MOUSE      = 1;

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -4665,16 +4665,17 @@ pref("full-screen-api.transition-duratio
 // timeout for black screen in fullscreen transition, unit: ms
 pref("full-screen-api.transition.timeout", 1000);
 // time for the warning box stays on the screen before sliding out, unit: ms
 pref("full-screen-api.warning.timeout", 3000);
 // delay for the warning box to show when pointer stays on the top, unit: ms
 pref("full-screen-api.warning.delay", 500);
 
 // DOM pointerlock API
+pref("pointer-lock-api.prefixed.enabled", false);
 // time for the warning box stays on the screen before sliding out, unit: ms
 pref("pointer-lock-api.warning.timeout", 3000);
 
 // DOM idle observers API
 pref("dom.idle-observers-api.enabled", true);
 
 // Time limit, in milliseconds, for EventStateManager::IsHandlingUserInput().
 // Used to detect long running handlers of user-generated events.