Make event renames optional, not mandatory.

lib/html/dart2js/html_dart2js.dart

Index: lib/html/dart2js/html_dart2js.dart
diff --git a/lib/html/dart2js/html_dart2js.dart b/lib/html/dart2js/html_dart2js.dart
index dcc8123d38211f738e7a2dad74b09bc63f1e5ce0..e3ece75bd5aae4cc5e0d3607f43f690d2e4e71e9 100644
--- a/lib/html/dart2js/html_dart2js.dart
+++ b/lib/html/dart2js/html_dart2js.dart
@@ -10324,10 +10324,6 @@ abstract class DocumentEvents implements ElementEvents {
 
   EventListenerList get focus;
 
-  EventListenerList get fullscreenChange;
-
-  EventListenerList get fullscreenError;
-
   EventListenerList get input;
 
   EventListenerList get invalid;
@@ -10354,10 +10350,6 @@ abstract class DocumentEvents implements ElementEvents {
 
   EventListenerList get paste;
 
-  EventListenerList get pointerLockChange;
-
-  EventListenerList get pointerLockError;
-
   EventListenerList get readyStateChange;
 
   EventListenerList get reset;
@@ -10368,10 +10360,10 @@ abstract class DocumentEvents implements ElementEvents {
 
   EventListenerList get select;
 
-  EventListenerList get selectStart;
-
   EventListenerList get selectionChange;
 
+  EventListenerList get selectStart;
+
   EventListenerList get submit;
 
   EventListenerList get touchCancel;
@@ -10381,6 +10373,14 @@ abstract class DocumentEvents implements ElementEvents {
   EventListenerList get touchMove;
 
   EventListenerList get touchStart;
+
+  EventListenerList get fullscreenChange;
+
+  EventListenerList get fullscreenError;
+
+  EventListenerList get pointerLockChange;
+
+  EventListenerList get pointerLockError;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -10976,10 +10976,6 @@ class _DocumentEventsImpl extends _ElementEventsImpl implements DocumentEvents {
 
   EventListenerList get focus => this['focus'];
 
-  EventListenerList get fullscreenChange => this['webkitfullscreenchange'];
-
-  EventListenerList get fullscreenError => this['webkitfullscreenerror'];
-
   EventListenerList get input => this['input'];
 
   EventListenerList get invalid => this['invalid'];
@@ -11006,10 +11002,6 @@ class _DocumentEventsImpl extends _ElementEventsImpl implements DocumentEvents {
 
   EventListenerList get paste => this['paste'];
 
-  EventListenerList get pointerLockChange => this['webkitpointerlockchange'];
-
-  EventListenerList get pointerLockError => this['webkitpointerlockerror'];
-
   EventListenerList get readyStateChange => this['readystatechange'];
 
   EventListenerList get reset => this['reset'];
@@ -11020,10 +11012,10 @@ class _DocumentEventsImpl extends _ElementEventsImpl implements DocumentEvents {
 
   EventListenerList get select => this['select'];
 
-  EventListenerList get selectStart => this['selectstart'];
-
   EventListenerList get selectionChange => this['selectionchange'];
 
+  EventListenerList get selectStart => this['selectstart'];
+
   EventListenerList get submit => this['submit'];
 
   EventListenerList get touchCancel => this['touchcancel'];
@@ -11033,6 +11025,14 @@ class _DocumentEventsImpl extends _ElementEventsImpl implements DocumentEvents {
   EventListenerList get touchMove => this['touchmove'];
 
   EventListenerList get touchStart => this['touchstart'];
+
+  EventListenerList get fullscreenChange => this['webkitfullscreenchange'];
+
+  EventListenerList get fullscreenError => this['webkitfullscreenerror'];
+
+  EventListenerList get pointerLockChange => this['webkitpointerlockchange'];
+
+  EventListenerList get pointerLockError => this['webkitpointerlockerror'];
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -11507,10 +11507,6 @@ abstract class ElementEvents implements Events {
 
   EventListenerList get focus;
 
-  EventListenerList get fullscreenChange;
-
-  EventListenerList get fullscreenError;
-
   EventListenerList get input;
 
   EventListenerList get invalid;
@@ -11562,6 +11558,10 @@ abstract class ElementEvents implements Events {
   EventListenerList get touchStart;
 
   EventListenerList get transitionEnd;
+
+  EventListenerList get fullscreenChange;
+
+  EventListenerList get fullscreenError;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -12601,10 +12601,6 @@ class _ElementEventsImpl extends _EventsImpl implements ElementEvents {
 
   EventListenerList get focus => this['focus'];
 
-  EventListenerList get fullscreenChange => this['webkitfullscreenchange'];
-
-  EventListenerList get fullscreenError => this['webkitfullscreenerror'];
-
   EventListenerList get input => this['input'];
 
   EventListenerList get invalid => this['invalid'];
@@ -12655,6 +12651,10 @@ class _ElementEventsImpl extends _EventsImpl implements ElementEvents {
 
   EventListenerList get transitionEnd => this['webkitTransitionEnd'];
 
+  EventListenerList get fullscreenChange => this['webkitfullscreenchange'];
+
+  EventListenerList get fullscreenError => this['webkitfullscreenerror'];
+
   EventListenerList get mouseWheel {
     if (JS('bool', '#.onwheel !== undefined', _ptr)) {
       // W3C spec, and should be IE9+, but IE has a bug exposing onwheel.
@@ -18744,19 +18744,11 @@ abstract class MediaElementEvents implements ElementEvents {
 
   EventListenerList get ended;
 
-  EventListenerList get keyAdded;
-
-  EventListenerList get keyError;
-
-  EventListenerList get keyMessage;
-
-  EventListenerList get loadStart;
-
   EventListenerList get loadedData;
 
   EventListenerList get loadedMetadata;
 
-  EventListenerList get needKey;
+  EventListenerList get loadStart;
 
   EventListenerList get pause;
 
@@ -18783,6 +18775,14 @@ abstract class MediaElementEvents implements ElementEvents {
   EventListenerList get volumeChange;
 
   EventListenerList get waiting;
+
+  EventListenerList get keyAdded;
+
+  EventListenerList get keyError;
+
+  EventListenerList get keyMessage;
+
+  EventListenerList get needKey;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -18919,19 +18919,11 @@ class _MediaElementEventsImpl extends _ElementEventsImpl implements MediaElement
 
   EventListenerList get ended => this['ended'];
 
-  EventListenerList get keyAdded => this['webkitkeyadded'];
-
-  EventListenerList get keyError => this['webkitkeyerror'];
-
-  EventListenerList get keyMessage => this['webkitkeymessage'];
-
-  EventListenerList get loadStart => this['loadstart'];
-
   EventListenerList get loadedData => this['loadeddata'];
 
   EventListenerList get loadedMetadata => this['loadedmetadata'];
 
-  EventListenerList get needKey => this['webkitneedkey'];
+  EventListenerList get loadStart => this['loadstart'];
 
   EventListenerList get pause => this['pause'];
 
@@ -18958,6 +18950,14 @@ class _MediaElementEventsImpl extends _ElementEventsImpl implements MediaElement
   EventListenerList get volumeChange => this['volumechange'];
 
   EventListenerList get waiting => this['waiting'];
+
+  EventListenerList get keyAdded => this['webkitkeyadded'];
+
+  EventListenerList get keyError => this['webkitkeyerror'];
+
+  EventListenerList get keyMessage => this['webkitkeymessage'];
+
+  EventListenerList get needKey => this['webkitneedkey'];
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -37823,13 +37823,9 @@ abstract class Window implements EventTarget {
 
 abstract class WindowEvents implements Events {
 
-  EventListenerList get abort;
-
-  EventListenerList get animationEnd;
-
-  EventListenerList get animationIteration;
+  EventListenerList get contentLoaded;
 
-  EventListenerList get animationStart;
+  EventListenerList get abort;
 
   EventListenerList get beforeUnload;
 
@@ -37843,16 +37839,14 @@ abstract class WindowEvents implements Events {
 
   EventListenerList get click;
 
-  EventListenerList get contentLoaded;
-
   EventListenerList get contextMenu;
 
+  EventListenerList get doubleClick;
+
   EventListenerList get deviceMotion;
 
   EventListenerList get deviceOrientation;
 
-  EventListenerList get doubleClick;
-
   EventListenerList get drag;
 
   EventListenerList get dragEnd;
@@ -37891,12 +37885,12 @@ abstract class WindowEvents implements Events {
 
   EventListenerList get load;
 
-  EventListenerList get loadStart;
-
   EventListenerList get loadedData;
 
   EventListenerList get loadedMetadata;
 
+  EventListenerList get loadStart;
+
   EventListenerList get message;
 
   EventListenerList get mouseDown;
@@ -37963,13 +37957,19 @@ abstract class WindowEvents implements Events {
 
   EventListenerList get touchStart;
 
-  EventListenerList get transitionEnd;
-
   EventListenerList get unload;
 
   EventListenerList get volumeChange;
 
   EventListenerList get waiting;
+
+  EventListenerList get animationEnd;
+
+  EventListenerList get animationIteration;
+
+  EventListenerList get animationStart;
+
+  EventListenerList get transitionEnd;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -38292,13 +38292,9 @@ class _WindowImpl extends _EventTargetImpl implements Window native "@*DOMWindow
 class _WindowEventsImpl extends _EventsImpl implements WindowEvents {
   _WindowEventsImpl(_ptr) : super(_ptr);
 
-  EventListenerList get abort => this['abort'];
-
-  EventListenerList get animationEnd => this['webkitAnimationEnd'];
-
-  EventListenerList get animationIteration => this['webkitAnimationIteration'];
+  EventListenerList get contentLoaded => this['DOMContentLoaded'];
 
-  EventListenerList get animationStart => this['webkitAnimationStart'];
+  EventListenerList get abort => this['abort'];
 
   EventListenerList get beforeUnload => this['beforeunload'];
 
@@ -38312,16 +38308,14 @@ class _WindowEventsImpl extends _EventsImpl implements WindowEvents {
 
   EventListenerList get click => this['click'];
 
-  EventListenerList get contentLoaded => this['DOMContentLoaded'];
-
   EventListenerList get contextMenu => this['contextmenu'];
 
+  EventListenerList get doubleClick => this['dblclick'];
+
   EventListenerList get deviceMotion => this['devicemotion'];
 
   EventListenerList get deviceOrientation => this['deviceorientation'];
 
-  EventListenerList get doubleClick => this['dblclick'];
-
   EventListenerList get drag => this['drag'];
 
   EventListenerList get dragEnd => this['dragend'];
@@ -38360,12 +38354,12 @@ class _WindowEventsImpl extends _EventsImpl implements WindowEvents {
 
   EventListenerList get load => this['load'];
 
-  EventListenerList get loadStart => this['loadstart'];
-
   EventListenerList get loadedData => this['loadeddata'];
 
   EventListenerList get loadedMetadata => this['loadedmetadata'];
 
+  EventListenerList get loadStart => this['loadstart'];
+
   EventListenerList get message => this['message'];
 
   EventListenerList get mouseDown => this['mousedown'];
@@ -38432,13 +38426,19 @@ class _WindowEventsImpl extends _EventsImpl implements WindowEvents {
 
   EventListenerList get touchStart => this['touchstart'];
 
-  EventListenerList get transitionEnd => this['webkitTransitionEnd'];
-
   EventListenerList get unload => this['unload'];
 
   EventListenerList get volumeChange => this['volumechange'];
 
   EventListenerList get waiting => this['waiting'];
+
+  EventListenerList get animationEnd => this['webkitAnimationEnd'];
+
+  EventListenerList get animationIteration => this['webkitAnimationIteration'];
+
+  EventListenerList get animationStart => this['webkitAnimationStart'];
+
+  EventListenerList get transitionEnd => this['webkitTransitionEnd'];
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a