Improve Blob constructor error messages.

Source/bindings/v8/V8Utilities.cpp

 /*
  * Copyright (C) 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 58 matching lines @@
     if (isUndefinedOrNull(value)) {
         ports.resize(0);
         arrayBuffers.resize(0);
         return true;
     }
 
     uint32_t length = 0;
     if (value->IsArray()) {
         v8::Local<v8::Array> array = v8::Local<v8::Array>::Cast(value);
         length = array->Length();
-    } else {
-        if (toV8Sequence(value, length, notASequence, isolate).IsEmpty())
-            return false;
+    } else if (toV8Sequence(value, length, isolate).IsEmpty()) {
+        notASequence = true;
+        return false;
     }
 
     v8::Local<v8::Object> transferrables = v8::Local<v8::Object>::Cast(value);
 
     // Validate the passed array of transferrables.
     for (unsigned int i = 0; i < length; ++i) {
         v8::Local<v8::Value> transferrable = transferrables->Get(i);
         // Validation of non-null objects, per HTML5 spec 10.3.3.
         if (isUndefinedOrNull(transferrable)) {
             setDOMException(DataCloneError, isolate);
@@ skipping 80 matching lines @@
 
 ExecutionContext* getExecutionContext()
 {
     if (WorkerScriptController* controller = WorkerScriptController::controllerForContext())
         return &controller->workerGlobalScope();
 
     return currentDocument();
 }
 
 } // namespace WebCore