Include what you use in accessors.{h,cc}.

include/v8stdint.h

-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
@@ skipping 11 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Load definitions of standard types.
 
 #ifndef V8STDINT_H_
 #define V8STDINT_H_
 
+#include <stddef.h>
 #include <stdio.h>
 
 #if defined(_WIN32) && !defined(__MINGW32__)
 
 typedef signed char int8_t;
 typedef unsigned char uint8_t;
 typedef short int16_t;  // NOLINT
 typedef unsigned short uint16_t;  // NOLINT
 typedef int int32_t;
 typedef unsigned int uint32_t;
 typedef __int64 int64_t;
 typedef unsigned __int64 uint64_t;
 // intptr_t and friends are defined in crtdefs.h through stdio.h.
 
 #else
 
 #include <stdint.h>
 
 #endif
 
 #endif  // V8STDINT_H_