r8425 (1081f75) had fixed this originally, but those changes were
accidentally reverted when the experimental/gc branch was merged
at r9600.

BUG=
TEST=debug mozilla regress-137181

Review URL: http://codereview.chromium.org/9026006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10302 ce2b1a6d-e550-0410-aec6-3dcde31c8c00