Correct data size argument type in resource loading path to unsigned

Source/core/fetch/ImageResource.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 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 327 matching lines @@
 
 inline void ImageResource::clearImage()
 {
     // If our Image has an observer, it's always us so we need to clear the back pointer
     // before dropping our reference.
     if (m_image)
         m_image->setImageObserver(0);
     m_image.clear();
 }
 
-void ImageResource::appendData(const char* data, int length)
+void ImageResource::appendData(const char* data, unsigned length)
 {
     Resource::appendData(data, length);
     if (!m_loadingMultipartContent)
         updateImage(false);
 }
 
 void ImageResource::updateImage(bool allDataReceived)
 {
     TRACE_EVENT0("blink", "ImageResource::updateImage");
 
@@ skipping 130 matching lines @@
 bool ImageResource::isAccessAllowed(SecurityOrigin* securityOrigin)
 {
     if (!image()->currentFrameHasSingleSecurityOrigin())
         return false;
     if (passesAccessControlCheck(securityOrigin))
         return true;
     return !securityOrigin->taintsCanvas(response().url());
 }
 
 } // namespace blink