Switch to standard integer types in ios/.

ios/web/string_util.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ios/web/public/string_util.h"
 
+#include <stddef.h>
+
 #include "base/strings/string_util.h"
 
 namespace web {
 
 base::string16 GetStringByClippingLastWord(const base::string16& contents,
                                            size_t length) {
   if (contents.size() < length)
     return contents;
 
   base::string16 clipped_contents = contents.substr(0, length);
   size_t last_space_index =
       clipped_contents.find_last_of(base::kWhitespaceUTF16);
   // TODO(droger): Check if we should return the empty string instead.
   // See http://crbug.com/324304
   if (last_space_index != base::string16::npos)
     clipped_contents.resize(last_space_index);
   return clipped_contents;
 }
 
 }  // namespace web