This reverts r9975.  This change broke (at least) snapshots on x64.

TBR=fschneider@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/8540005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9976 ce2b1a6d-e550-0410-aec6-3dcde31c8c00