Breaks compilation on Mac64

| TEST=compiler-unittests
| R=jarin@chromium.org
|
| Committed: https://code.google.com/p/v8/source/detail?r=23077

TBR=bmeurer@chromium.org,jarin@chromium.org
LOG=n
BUG=none

Review URL: https://codereview.chromium.org/456843004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23079 ce2b1a6d-e550-0410-aec6-3dcde31c8c00