Add fast-variants feature to test driver.

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/704723002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25139 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Don't use C++11's std::trunc and std::round, use the traditional C functions.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/703893002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25140 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
[turbofan] Propagate "deferredness" to dominated basic blocks.

TEST=cctest/test-scheduler
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/686273005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25141 ce2b1a6d-e550-0410-aec6-3dcde31c8c00