Make Element.animate work in dart2js Chrome

tools/dom/templates/html/impl/impl_Element.darttemplate

Index: tools/dom/templates/html/impl/impl_Element.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Element.darttemplate b/tools/dom/templates/html/impl/impl_Element.darttemplate
index 38209ae33b6301370ed3aecf4ea85e2873b93b50..a41c6a6831db92c61746f14cf2f01f926dc5e362 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -779,6 +779,57 @@ $(ANNOTATIONS)$(NATIVESPEC)abstract class $CLASSNAME$EXTENDS$IMPLEMENTS {
   @deprecated
   void leftView() {}
 
+$if DART2JS
+  /**
+   * Creates a new AnimationEffect object whose target element is the object
+   * on which the method is called, and calls the play() method of the
+   * AnimationTimeline object of the document timeline of the node document
+   * of the element, passing the newly created AnimationEffect as the argument
+   * to the method. Returns an AnimationPlayer for the effect.
+   *
+   * Examples
+   *
+   *     var animation = elem.animate([{"opacity": 75}, {"opacity": 0}], 200);
+   *
+   *     var animation = elem.animate([
+   *       {"transform": "translate(100px, -100%)"},
+   *       {"transform" : "translate(400px, 500px)"}
+   *     ], 1500);  
+   *
+   * The [frames] parameter is an Iterable<Map>, where the
+   * map entries specify CSS animation effects. The
+   * [timing] paramter can be a double, representing the number of milliseconds
+   * for the transition, or a Map with fields corresponding to those
+   * of the [Timing] object.
+   *
+   * This is not yet supported in Dartium.
+  **/
+// TODO(alanknight): Correct above comment once it works in Dartium.
+  @Experimental
+  @SupportedBrowser(SupportedBrowser.CHROME, '36')
+  AnimationPlayer animate(Iterable<Map<String, dynamic>> frames, [timing]) {
+    if (frames is! Iterable || !(frames.every((x) => x is Map))) {
+      throw new ArgumentError("The frames parameter should be a List of Maps "
+          "with frame information");
+    }
+    var convertedFrames = frames;
+    if (convertedFrames is Iterable) {
+      convertedFrames = frames.map(convertDartToNative_Dictionary).toList();
+    }
+    var convertedTiming = timing;
+    if (convertedTiming is Map) {
+      convertedTiming = convertDartToNative_Dictionary(convertedTiming);
+    }
+    return convertedTiming == null
+      ? _animate(convertedFrames)
+      : _animate(convertedFrames, convertedTiming);
+  }
+
+  @DomName('Element.animate')
+  @JSName('animate')
+  @Experimental() // untriaged
+  AnimationPlayer _animate(Object effect, [timing]) native;
+$endif
   /**
    * Called by the DOM whenever an attribute on this has been changed.
    */