Minimal fix to get cross frame tests working, take #2.

lib/dom/templates/html/dartium/impl_IFrameElement.darttemplate

Index: lib/dom/templates/html/dartium/impl_IFrameElement.darttemplate
diff --git a/lib/dom/templates/html/dartium/impl_Window.darttemplate b/lib/dom/templates/html/dartium/impl_IFrameElement.darttemplate
similarity index 50%
copy from lib/dom/templates/html/dartium/impl_Window.darttemplate
copy to lib/dom/templates/html/dartium/impl_IFrameElement.darttemplate
index 0713050ab288c22451da77bfbd0059874961dfc3..9a2cbfa98f761859359b3077487285dc2419d353 100644
--- a/lib/dom/templates/html/dartium/impl_Window.darttemplate
+++ b/lib/dom/templates/html/dartium/impl_IFrameElement.darttemplate
@@ -4,14 +4,7 @@
 
 class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 
-  _DocumentImpl get document() => _wrap(_ptr.document);
-
-  void requestLayoutFrame(TimeoutHandler callback) {
-    _addMeasurementFrameCallback(callback);
-  }
-
-  int requestAnimationFrame(RequestAnimationFrameCallback callback) =>
-      webkitRequestAnimationFrame(callback);
+  Window get contentWindow() => _wrap(_ptr.contentWindow);
 
 $!MEMBERS
 }