Reduce redundant phi nodes after graph building.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/461003002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23075 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
ARM64: Enable TF tests.

Updated the test status file accordingly.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/459093002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23076 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Use CommonNodeCache for heap constants in ChangeLowering.

TEST=compiler-unittests
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/466673004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23077 ce2b1a6d-e550-0410-aec6-3dcde31c8c00