Revert "Don't call _ensureRequestAnimationFrame in Dartium."

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

Index: tools/dom/templates/html/impl/impl_Window.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Window.darttemplate b/tools/dom/templates/html/impl/impl_Window.darttemplate
index 6f56b8729cc81bf9471955817ec5208f6b3717f5..8abac3775c4146f65b923db522ae32ae4fa881ac 100644
--- a/tools/dom/templates/html/impl/impl_Window.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Window.darttemplate
@@ -96,8 +96,6 @@ $if DART2JS
     JS('void', '#.location = #', this, value);
   }
 
-$endif
-
   /**
    * Called to draw an animation frame and then request the window to repaint
    * after [callback] has finished (creating the animation).
@@ -116,9 +114,7 @@ $endif
    */
   @DomName('Window.requestAnimationFrame')
   int requestAnimationFrame(FrameRequestCallback callback) {
-$if DART2JS
     _ensureRequestAnimationFrame();
-$endif
     return _requestAnimationFrame(_wrapZone/*<num, dynamic>*/(callback));
   }
 
@@ -130,15 +126,11 @@ $endif
    * * [Window.cancelAnimationFrame](https://developer.mozilla.org/en-US/docs/Web/API/Window.cancelAnimationFrame)
    *   from MDN.
    */
-  @DomName('Window.cancelAnimationFrame')
   void cancelAnimationFrame(int id) {
-$if DART2JS
     _ensureRequestAnimationFrame();
-$endif
     _cancelAnimationFrame(id);
   }
 
-$if DART2JS
   @JSName('requestAnimationFrame')
   int _requestAnimationFrame(FrameRequestCallback callback) native;
 
@@ -189,6 +181,28 @@ $if DART2JS
   /// The debugging console for this window.
   @DomName('Window.console')
   Console get console => Console._safeConsole;
+
+$else
+  /**
+   * Called to draw an animation frame and then request the window to repaint
+   * after [callback] has finished (creating the animation).
+   *
+   * Use this method only if you need to later call [cancelAnimationFrame]. If
+   * not, the preferred Dart idiom is to set animation frames by calling
+   * [animationFrame], which returns a Future.
+   *
+   * Returns a non-zero valued integer to represent the request id for this
+   * request. This value only needs to be saved if you intend to call
+   * [cancelAnimationFrame] so you can specify the particular animation to
+   * cancel.
+   *
+   * Note: The supplied [callback] needs to call [requestAnimationFrame] again
+   * for the animation to continue.
+   */
+  @DomName('Window.requestAnimationFrame')
+  int requestAnimationFrame(FrameRequestCallback callback) {
+    return _requestAnimationFrame(_wrapZone(callback));
+  }
 $endif
 
   /**