Fix issue when compiling with gcc 4.6.

src/utils.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_UTILS_H_
 #define V8_UTILS_H_
 
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 1417 matching lines @@
       memcpy(dest, src, 15);
       break;
     default:
       MemCopy(dest, src, chars);
       break;
   }
 }
 
 
 void CopyCharsUnsigned(uint16_t* dest, const uint8_t* src, size_t chars) {
-  if (chars >= kMinComplexConvertMemCopy) {
+  if (chars >= static_cast<size_t>(kMinComplexConvertMemCopy)) {
     MemCopyUint16Uint8(dest, src, chars);
   } else {
     MemCopyUint16Uint8Wrapper(dest, src, chars);
   }
 }
 
 
 void CopyCharsUnsigned(uint16_t* dest, const uint16_t* src, size_t chars) {
   switch (static_cast<unsigned>(chars)) {
     case 0:
@@ skipping 226 matching lines @@
   // Takes the address of the limit variable in order to find out where
   // the top of stack is right now.
   uintptr_t limit = reinterpret_cast<uintptr_t>(&limit);
   return limit;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_UTILS_H_