Merge regexp codeflushing (r8532+r8560) to the 3.3 branch.

test/mjsunit/regress/regress-regexp-codeflush.js

 // Copyright 2011 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
@@ skipping 35 matching lines @@
   var x = "s foo s bar s foo s bar s";
   x = x + x;
   x = x + x;
   x = x + x;
   x = x + x;
   x = x + x;
   x = x + x;
   x = x + x;
   x.replace(re, foo);
 }