Fix fast-variants feature in test driver.

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/701933003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25150 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
[turbofan] Fix deopt for assignments in non-effect context.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/701853002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25151 ce2b1a6d-e550-0410-aec6-3dcde31c8c00