Remove 'String::append' from some of the blink source.

Source/core/fetch/ScriptResource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 13 matching lines @@
     pages from the web. It has a memory cache for these objects.
 */
 
 #include "config.h"
 #include "core/fetch/ScriptResource.h"
 
 #include "core/fetch/TextResourceDecoder.h"
 #include "platform/MIMETypeRegistry.h"
 #include "platform/SharedBuffer.h"
 #include "platform/network/HTTPParsers.h"
+#include "wtf/text/StringBuilder.h"
 
 namespace WebCore {
 
 ScriptResource::ScriptResource(const ResourceRequest& resourceRequest, const String& charset)
     : Resource(resourceRequest, Script)
     , m_decoder(TextResourceDecoder::create("application/javascript", charset))
 {
     DEFINE_STATIC_LOCAL(const AtomicString, acceptScript, ("*/*", AtomicString::ConstructFromLiteral));
 
     // It's javascript we want.
@@ skipping 20 matching lines @@
 {
     return extractMIMETypeFromMediaType(m_response.httpHeaderField("Content-Type")).lower();
 }
 
 const String& ScriptResource::script()
 {
     ASSERT(!isPurgeable());
     ASSERT(isLoaded());
 
     if (!m_script && m_data) {
-        String script = m_decoder->decode(m_data->data(), encodedSize());
+        StringBuilder script;
+        script.append(m_decoder->decode(m_data->data(), encodedSize()));
         script.append(m_decoder->flush());
         m_data.clear();
         // We lie a it here and claim that script counts as encoded data (even though it's really decoded data).
         // That's because the MemoryCache thinks that it can clear out decoded data by calling destroyDecodedData(),
         // but we can't destroy script in destroyDecodedData because that's our only copy of the data!
         setEncodedSize(script.sizeInBytes());
-        m_script = script;
+        m_script = script.toString();
     }
 
     return m_script.string();
 }
 
 bool ScriptResource::mimeTypeAllowedByNosniff() const
 {
     return parseContentTypeOptionsHeader(m_response.httpHeaderField("X-Content-Type-Options")) != ContentTypeOptionsNosniff || MIMETypeRegistry::isSupportedJavaScriptMIMEType(mimeType());
 }
 
 } // namespace WebCore