Registration-based approach to cross frame support.

pkg/dev_compiler/tool/input_sdk/private/js_helper.dart

Index: pkg/dev_compiler/tool/input_sdk/private/js_helper.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/js_helper.dart b/pkg/dev_compiler/tool/input_sdk/private/js_helper.dart
index ab0c443b6b333c323dd51fb1cf18eeefb80683f2..eb932e36bec893ff25712425f124fbef708da2f5 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/js_helper.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/js_helper.dart
@@ -907,5 +907,9 @@ class BooleanConversionAssertionError extends AssertionError {
   toString() => 'Failed assertion: boolean expression must not be null';
 }
 
-// Hook to register new global object.
-void registerGlobalObject(object) {}
+// Hook to register new global object.  This is invoked from dart:html
+// whenever a new window is accessed for the first time.
+void registerGlobalObject(object) {
+  dart.polyfill(object);
+  dart.applyAllExtensions(object);
+}