Remove outdated assertion scope.

R=jkummerow@chromium.org
BUG=349870
LOG=N

Review URL: https://codereview.chromium.org/182003004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19687 ce2b1a6d-e550-0410-aec6-3dcde31c8c00