Do not change environment between simulate and scope with no observable side-effects...

Do not change environment between simulate and scope with no observable side-effects in HandlePropertyAssignment.

LChunkBuilder reconstructs the environment by applying simulates. A scope with no observable side-effects has no simulates. If the scope deoptimizes, then LChunkBuilder would miss the changes to the environment between the last simulate and the scope.

R=danno@chromium.org
BUG=v8:2671
TEST=mjsunit/regress/regress-2671.js

Review URL: https://chromiumcodereview.appspot.com/14793009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14584 ce2b1a6d-e550-0410-aec6-3dcde31c8c00