Improve TypeError messages from failed array conversions.

Source/bindings/v8/V8Utilities.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 45 matching lines @@
     typedef WTF::Vector<RefPtr<MessagePort>, 1> MessagePortArray;
     typedef WTF::Vector<RefPtr<ArrayBuffer>, 1> ArrayBufferArray;
 
     // Helper function which pulls the values out of a JS sequence and into a MessagePortArray.
     // Also validates the elements per sections 4.1.13 and 4.1.15 of the WebIDL spec and section 8.3.3
     // of the HTML5 spec and generates exceptions as appropriate. If the supplied argument's type isn't
     // a JS sequence, a type error is signalled by setting 'notASequence' to true -- the caller
     // then being responsible for generating a TypeError having a message that fits the context.
     // Returns true if the array was filled, or false if the passed value was not of an appropriate type.
     bool extractTransferables(v8::Local<v8::Value>, MessagePortArray&, ArrayBufferArray&, bool& notASequence, v8::Isolate*);
-    bool getMessagePortArray(v8::Local<v8::Value>, MessagePortArray&, v8::Isolate*);
+
+    bool getMessagePortArray(v8::Local<v8::Value>, const String& propertyName, MessagePortArray&, v8::Isolate*);
+    bool getMessagePortArray(v8::Local<v8::Value>, int argumentIndex, MessagePortArray&, v8::Isolate*);
 
 } // namespace WebCore
 
 #endif // V8Utilities_h