This re-applies r4220 and r4233, which was reverted in r4254 due to a bug. This bug has now been fixed, with the only change being line 2884 changed from

  __ SmiTag(left_side->reg());

to

  __ SmiTag(operand->reg());

Added a regression test.

BUG=http://crbug.com/39160
TEST=test/mjsunit/regress/regress-crbug-39160.js

Review URL: http://codereview.chromium.org/1251009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4261 ce2b1a6d-e550-0410-aec6-3dcde31c8c00