Sync some event interfaces with the HTML spec

Source/core/events/MessageEvent.idl

Index: Source/core/events/MessageEvent.idl
diff --git a/Source/core/events/MessageEvent.idl b/Source/core/events/MessageEvent.idl
index 2dea4ed9fd661aeff1c08bc2cf5f85b3d7d115ac..588a9397f371543fcd79ae406553a67b5ae516e7 100644
--- a/Source/core/events/MessageEvent.idl
+++ b/Source/core/events/MessageEvent.idl
@@ -32,11 +32,15 @@
     Exposed=(Window,Worker),
     RaisesException=Constructor,
 ] interface MessageEvent : Event {
+    [Custom=Getter] readonly attribute any data;
     readonly attribute DOMString origin;
     readonly attribute DOMString lastEventId;
-    readonly attribute EventTarget? source; // May be a Window or a MessagePort
-    [Custom=Getter] readonly attribute any data;
+    // TODO(bashi): |source| should be (WindowProxy or MessagePort)?
+    readonly attribute EventTarget? source;
     readonly attribute MessagePort[]? ports;
+
+    // TODO(philipj): None of the initMessageEvent() arguments should be
+    // optional, and |sourceArg| and |portsArg| are of the wrong type.
     [Custom, MeasureAs=InitMessageEvent] void initMessageEvent([Default=Undefined] optional DOMString typeArg,
                                    [Default=Undefined] optional boolean canBubbleArg,
                                    [Default=Undefined] optional boolean cancelableArg,
@@ -44,5 +48,5 @@
                                    [Default=Undefined] optional DOMString originArg,
                                    [Default=Undefined] optional DOMString lastEventIdArg,
                                    [Default=Undefined] optional Window sourceArg,
-                                   [Default=Undefined] optional MessagePort[] messagePorts);
+                                   [Default=Undefined] optional MessagePort[] portsArg);
 };