XMLHttpRequest#responseText should use a rope

Source/core/inspector/InspectorResourceAgent.h

Index: Source/core/inspector/InspectorResourceAgent.h
diff --git a/Source/core/inspector/InspectorResourceAgent.h b/Source/core/inspector/InspectorResourceAgent.h
index aeb1cdd9a9928a68248821e5ce954f24900e0938..40827c633658bbee10a01509a1850ae7968fdc1a 100644
--- a/Source/core/inspector/InspectorResourceAgent.h
+++ b/Source/core/inspector/InspectorResourceAgent.h
@@ -32,6 +32,7 @@
 #define InspectorResourceAgent_h
 
 #include "InspectorFrontend.h"
+#include "bindings/v8/ScriptString.h"
 #include "core/inspector/InspectorBaseAgent.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefCounted.h"
@@ -106,7 +107,7 @@ public:
     void documentThreadableLoaderStartedLoadingForClient(unsigned long identifier, ThreadableLoaderClient*);
     void willLoadXHR(ThreadableLoaderClient*, const String& method, const KURL&, bool async, PassRefPtr<FormData> body, const HTTPHeaderMap& headers, bool includeCrendentials);
     void didFailXHRLoading(ThreadableLoaderClient*);
-    void didFinishXHRLoading(ThreadableLoaderClient*, unsigned long identifier, const String& sourceString, const String&, const String&, unsigned);
+    void didFinishXHRLoading(ThreadableLoaderClient*, unsigned long identifier, ScriptString sourceString, const String&, const String&, unsigned);
     void didReceiveXHRResponse(unsigned long identifier);
     void willLoadXHRSynchronously();
     void didLoadXHRSynchronously();