Fix continue statements within for-in loops.

R=titzer@chromium.org
TEST=cctest/test-run-jsbranches/ForInContinueStatement
BUG=v8:3522
LOG=N

Review URL: https://codereview.chromium.org/502043002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23369 ce2b1a6d-e550-0410-aec6-3dcde31c8c00