This would happen when checking the current resource vs the prior one.
Calling GetResource would increment the reference count, but we would
not properly call Release.

BUG=angleproject:1710

Change-Id: Iefa9ee60929b9808985649c83f6322c1043fa5ed
Reviewed-on: https://chromium-review.googlesource.com/434801Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>