[arm64] Turn Word64And into tst instruction when possible.

Also add corresponding unit tests.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/684813004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24974 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
harmony-scoping: Correct dynamic lookups on a top level.

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/650663003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24975 ce2b1a6d-e550-0410-aec6-3dcde31c8c00