Correct data size argument type in resource loading path to unsigned

Source/core/fileapi/FileReaderLoader.cpp

 /*
  * Copyright (C) 2010 Google Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 209 matching lines @@
         if (initialBufferLength >= 0) {
             // Total size is known. Set m_rawData to ignore overflowed data.
             m_rawData->setVariableCapacity(false);
         }
     }
 
     if (m_client)
         m_client->didStartLoading();
 }
 
-void FileReaderLoader::didReceiveData(const char* data, int dataLength)
+void FileReaderLoader::didReceiveData(const char* data, unsigned dataLength)
 {
     ASSERT(data);
-    ASSERT(dataLength > 0);
 
     // Bail out if we already encountered an error.
     if (m_errorCode)
         return;
 
     if (m_readType == ReadByClient) {
         m_bytesLoaded += dataLength;
 
         if (m_client)
             m_client->didReceiveDataForClient(data, dataLength);
         return;
     }
 
-    unsigned bytesAppended = m_rawData->append(data, static_cast<unsigned>(dataLength));
+    unsigned bytesAppended = m_rawData->append(data, dataLength);
     if (!bytesAppended) {
         m_rawData.clear();
         m_bytesLoaded = 0;
         failed(FileError::NOT_READABLE_ERR);
         return;
     }
     m_bytesLoaded += bytesAppended;
     m_isRawDataConverted = false;
 
     if (m_client)
@@ skipping 142 matching lines @@
     m_stringResult = builder.toString();
 }
 
 void FileReaderLoader::setEncoding(const String& encoding)
 {
     if (!encoding.isEmpty())
         m_encoding = WTF::TextEncoding(encoding);
 }
 
 } // namespace blink