Revert "Patched in Dartium JsInterop"

tests/html/messageevent_test.dart

Index: tests/html/messageevent_test.dart
diff --git a/tests/html/messageevent_test.dart b/tests/html/messageevent_test.dart
index 86348fdd820b4174d65aff7087473f7489dae9eb..9ef36819ffc2a016e52044796e9306a87cede253 100644
--- a/tests/html/messageevent_test.dart
+++ b/tests/html/messageevent_test.dart
@@ -17,7 +17,7 @@ main() {
       expect(event.origin, equals('origin'));
       // IE allows setting this but just ignores it.
       // expect(event.lastEventId, equals('lastEventId'));
-      expect(event.source, window);
+      expect(event.source, same(window));
       // TODO(antonm): accessing ports is not supported yet.
   });
 }