Rollback of r14587 in trunk branch.

Bias commutative single-use register inputs and support lea adds

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/14680011

git-svn-id: https://v8.googlecode.com/svn/trunk@14640 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merged r14638 into trunk branch.

Fix missing hole check for loads from Smi arrays when all uses are changes

BUG=chromium:233737
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/15011010

git-svn-id: https://v8.googlecode.com/svn/trunk@14642 ce2b1a6d-e550-0410-aec6-3dcde31c8c00