Check that FPU TOP register is zero and clear all exceptions instead of using fninit,
which causes performance regression on Windows.

BUG=168370
R=danno@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11962015

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13401 ce2b1a6d-e550-0410-aec6-3dcde31c8c00