Reland "Refactoring: Make gtest testsuite the default."

BUG=v8:3489
TBR=bmeurer@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/533603002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23585 ce2b1a6d-e550-0410-aec6-3dcde31c8c00