Fix presubmit error

TBR=whesse@chromium.org
Review URL: http://codereview.chromium.org/6008010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6144 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/platform-macos.cc

@@ -29,7 +29,6 @@
 // the implementation is in platform-posix.cc.
 
 #include <dlfcn.h>
-#include <string>
 #include <unistd.h>
 #include <sys/mman.h>
 #include <mach/mach_init.h>
@@ -51,9 +50,10 @@
 #include <sys/types.h>
 #include <stdarg.h>
 #include <stdlib.h>
-
 #include <errno.h>
 
+#include <string>
+
 #undef MAP_TYPE
 
 #include "v8.h"