Correct data size argument type in resource loading path to unsigned

Source/core/fetch/ResourceLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2007 Graham Dennis (graham.dennis@gmail.com)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 416 matching lines @@
     // Reference the object in this method since the additional processing can do
     // anything including removing the last reference to this object.
     RefPtrWillBeRawPtr<ResourceLoader> protect(this);
 
     // FIXME: If we get a resource with more than 2B bytes, this code won't do the right thing.
     // However, with today's computers and networking speeds, this won't happen in practice.
     // Could be an issue with a giant local file.
     m_host->didReceiveData(m_resource, data, length, encodedDataLength);
     if (m_state == Terminated)
         return;
+    RELEASE_ASSERT(length >= 0);
     m_resource->appendData(data, length);
 }
 
 void ResourceLoader::didFinishLoading(blink::WebURLLoader*, double finishTime, int64 encodedDataLength)
 {
     RELEASE_ASSERT(m_connectionState == ConnectionStateReceivedResponse || m_connectionState == ConnectionStateReceivingData);
     m_connectionState = ConnectionStateFinishedLoading;
     if (m_state != Initialized)
         return;
     ASSERT(m_state != Terminated);
@@ skipping 81 matching lines @@
     didFinishLoading(0, monotonicallyIncreasingTime(), encodedDataLength);
 }
 
 ResourceRequest& ResourceLoader::applyOptions(ResourceRequest& request) const
 {
     request.setAllowStoredCredentials(m_options.allowCredentials == AllowStoredCredentials);
     return request;
 }
 
 }