Fix errors caused by unsafe conversions to/from size_t

third_party/WebKit/Source/platform/mhtml/MHTMLParser.cpp

 /*
  * Copyright (C) 2011 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 323 matching lines @@
         while (!(line = m_lineReader.nextChunkAsUTF8StringWithLatin1Fallback()).isNull()) {
             endOfArchiveReached = (line == endOfDocumentBoundary);
             if (checkBoundary && (line == endOfPartBoundary || endOfArchiveReached)) {
                 endOfPartReached = true;
                 break;
             }
             // Note that we use line.utf8() and not line.ascii() as ascii turns special characters (such as tab, line-feed...) into '?'.
             content->append(line.utf8().data(), line.length());
             if (contentTransferEncoding == MIMEHeader::QuotedPrintable) {
                 // The line reader removes the \r\n, but we need them for the content in this case as the QuotedPrintable decoder expects CR-LF terminated lines.
-                content->append("\r\n", 2);
+                content->append("\r\n", 2u);
             }
         }
     }
     if (!endOfPartReached && checkBoundary) {
         WTF_LOG_ERROR("No bounday found for MHTML part.");
         return nullptr;
     }
 
     Vector<char> data;
     switch (contentTransferEncoding) {
@@ skipping 60 matching lines @@
     if (!contentID.startsWith('<') || !contentID.endsWith('>'))
         return KURL();
 
     StringBuilder uriBuilder;
     uriBuilder.append("cid:");
     uriBuilder.append(contentID, 1, contentID.length() - 2);
     return KURL(KURL(), uriBuilder.toString());
 }
 
 } // namespace blink