Fix single release generation

Fix several cases where generating a single release will fail because
the object was defined at a previous release, and the UniqueRelease
check was returning an empty set.

BUG= 109679
Review URL: http://codereview.chromium.org/9151022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@117048 0039d316-1c4b-4281-b951-d872f2087c98
4 files changed