This creates a confusing result. It's better to let allocation sites
transition to their end state than artificially stop tracking at the
double/fast boundary.

BUG=
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/22868004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16820 ce2b1a6d-e550-0410-aec6-3dcde31c8c00