Add toWebCoreString() / toWebCoreAtomicString() overloads taking a v8::String

Source/bindings/v8/ScriptPreprocessor.cpp

 /*
  * Copyright (C) 2013 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 86 matching lines @@
     v8::Handle<v8::String> sourceCodeString = v8String(sourceCode, m_isolate);
     v8::Handle<v8::String> sourceNameString = v8String(sourceName, m_isolate);
     v8::Handle<v8::Value> argv[] = { sourceCodeString, sourceNameString, functionName};
 
     v8::TryCatch tryCatch;
     tryCatch.SetVerbose(true);
     TemporaryChange<bool> isPreprocessing(m_isPreprocessing, true);
     v8::Handle<v8::Value> resultValue = V8ScriptRunner::callAsFunction(m_preprocessorFunction.newLocal(m_isolate), m_context.newLocal(m_isolate)->Global(), WTF_ARRAY_LENGTH(argv), argv);
 
     if (!resultValue.IsEmpty() && resultValue->IsString())
-        return toWebCoreStringWithNullCheck(resultValue);
+        return toWebCoreStringWithNullCheck(resultValue.As<v8::String>());
 
     return sourceCode;
 }
 
 } // namespace WebCore