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

Source/core/fetch/ScriptResource.cpp

Index: Source/core/fetch/ScriptResource.cpp
diff --git a/Source/core/fetch/ScriptResource.cpp b/Source/core/fetch/ScriptResource.cpp
old mode 100644
new mode 100755
index 873ef3322722f711ff22d971252932b792fd5174..9137c80d61d3c7c37a206765e083f63b236eedb8
--- a/Source/core/fetch/ScriptResource.cpp
+++ b/Source/core/fetch/ScriptResource.cpp
@@ -31,6 +31,7 @@
 #include "platform/MIMETypeRegistry.h"
 #include "platform/SharedBuffer.h"
 #include "platform/network/HTTPParsers.h"
+#include "wtf/text/StringBuilder.h"
 
 namespace WebCore {
 
@@ -71,14 +72,15 @@ const String& ScriptResource::script()
     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();