Better handling of Phi nodes with constant inputs

Review URL: https://codereview.chromium.org/14471034

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14448 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Fix test/build failures (win64 compile warning, isolate test parallel compilation failure, gcmole issue, isolate test intermittant failure)

BUG=

Review URL: https://codereview.chromium.org/14265024

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14449 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Implement support for Math.imul in Crankshaft.

R=jkummerow@chromium.org
TEST=mjsunit/math-imul

Review URL: https://codereview.chromium.org/14471041

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14450 ce2b1a6d-e550-0410-aec6-3dcde31c8c00