Merged r14169 into 3.17 branch.

Fix worst-case behavior of MergeRemovableSimulates().

BUG=v8:2612
R=jkummerow@chromium.org

Review URL: https://chromiumcodereview.appspot.com/14472003

git-svn-id: https://v8.googlecode.com/svn/branches/3.17@14418 ce2b1a6d-e550-0410-aec6-3dcde31c8c00