Simplify invokeCallback() and support void return values for IDL callbacks

Source/bindings/v8/V8Callback.h

 /*
 * Copyright (C) 2012 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 22 matching lines @@
 
 #include "bindings/v8/V8Binding.h"
 #include "bindings/v8/V8Utilities.h"
 #include "core/dom/ExceptionCode.h"
 #include <v8.h>
 
 namespace WebCore {
 
 class ExecutionContext;
 
-bool invokeCallback(v8::Handle<v8::Object> callback, int argc, v8::Handle<v8::Value> argv[], bool& callbackReturnValue, ExecutionContext*, v8::Isolate*);
-bool invokeCallback(v8::Handle<v8::Object> callback, v8::Handle<v8::Object> thisObject, int argc, v8::Handle<v8::Value> argv[], bool& callbackReturnValue, ExecutionContext*, v8::Isolate*);
+// Returns false if the callback threw an exception, true otherwise.
+bool invokeCallback(v8::Local<v8::Function> callback, int argc, v8::Handle<v8::Value> argv[], ExecutionContext*, v8::Isolate*);
+bool invokeCallback(v8::Local<v8::Function> callback, v8::Handle<v8::Object> thisObject, int argc, v8::Handle<v8::Value> argv[], ExecutionContext*, v8::Isolate*);
 
 enum CallbackAllowedValueFlag {
     CallbackAllowUndefined = 1,
     CallbackAllowNull = 1 << 1
 };
 
 typedef unsigned CallbackAllowedValueFlags;
 
 // 'FunctionOnly' is assumed for the created callback.
 template <typename V8CallbackType>
@@ skipping 12 matching lines @@
         setDOMException(TypeMismatchError, isolate);
         return nullptr;
     }
 
     return V8CallbackType::create(v8::Handle<v8::Function>::Cast(value), getExecutionContext());
 }
 
 } // namespace WebCore
 
 #endif // V8Callback_h