Make sure heap is iteratable before iterating it.
Make sure heap is iteratable before iterating it.

This line was accidentally removed in r9489.

TBR=kmillikin@chromium.org

BUG=
TEST=

Review URL: http://codereview.chromium.org//8086018

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@9497 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh