Replace responseType mismatch handling code in XMLHttpRequest::responseJSONSource() with ASSERT

Source/core/xml/XMLHttpRequest.h

 /*
  *  Copyright (C) 2003, 2006, 2008 Apple Inc. All rights reserved.
  *  Copyright (C) 2005, 2006 Alexey Proskuryakov <ap@nypop.com>
  *  Copyright (C) 2011 Google Inc. All rights reserved.
  *  Copyright (C) 2012 Intel Corporation
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
@@ skipping 95 matching lines @@
     void send(Blob*, ExceptionState&);
     void send(DOMFormData*, ExceptionState&);
     void send(ArrayBuffer*, ExceptionState&);
     void send(ArrayBufferView*, ExceptionState&);
     void abort();
     void setRequestHeader(const AtomicString& name, const String& value, ExceptionState&);
     void overrideMimeType(const String& override);
     String getAllResponseHeaders(ExceptionState&) const;
     String getResponseHeader(const AtomicString& name, ExceptionState&) const;
     ScriptString responseText(ExceptionState&);
-    ScriptString responseJSONSource(ExceptionState&);
+    ScriptString responseJSONSource();
     Document* responseXML(ExceptionState&);
     Blob* responseBlob();
     unsigned long timeout() const { return m_timeoutMilliseconds; }
     void setTimeout(unsigned long timeout, ExceptionState&);
 
     void sendForInspectorXHRReplay(PassRefPtr<FormData>, ExceptionState&);
 
     // Expose HTTP validation methods for other untrusted requests.
     static bool isAllowedHTTPMethod(const String&);
     static String uppercaseKnownHTTPMethod(const String&);
@@ skipping 104 matching lines @@
 
     // An enum corresponding to the allowed string values for the responseType attribute.
     ResponseTypeCode m_responseTypeCode;
     Timer<XMLHttpRequest> m_protectionTimer;
     RefPtr<SecurityOrigin> m_securityOrigin;
 };
 
 } // namespace WebCore
 
 #endif // XMLHttpRequest_h