Browser compat for window.requestAnimationFrame

lib/dom/templates/html/frog/impl_Window.darttemplate

Index: lib/dom/templates/html/frog/impl_Window.darttemplate
diff --git a/lib/dom/templates/html/frog/impl_Window.darttemplate b/lib/dom/templates/html/frog/impl_Window.darttemplate
index 95d5abd910f315f546498bfa97f6afd98f4c5622..746e5921b9942d51f2d7496ff72eae38229d65ad 100644
--- a/lib/dom/templates/html/frog/impl_Window.darttemplate
+++ b/lib/dom/templates/html/frog/impl_Window.darttemplate
@@ -10,5 +10,23 @@ class $CLASSNAME$EXTENDS$IMPLEMENTS native "@*DOMWindow" {
     _addMeasurementFrameCallback(callback);
   }
 
+  /** @domName DOMWindow.requestAnimationFrame */
+  int requestAnimationFrame(RequestAnimationFrameCallback callback) native '''
+    if (!window.requestAnimationFrame) {
+      window.requestAnimationFrame =
+          window.webkitRequestAnimationFrame ||
+          window.mozRequestAnimationFrame ||
+          window.msRequestAnimationFrame ||
+          window.oRequestAnimationFrame ||
+          function (callback) {
+            window.setTimeout(callback, 16 /* 16ms ~= 60fps */);
+          };
+    }
+    return window.requestAnimationFrame(callback);
+''';
+
+  // Protect member 'requestAnimationFrame'.
+  _requestAnimationFrame() native 'requestAnimationFrame';
+
 $!MEMBERS
 }