tree d7c81955b05cb43f66c2d974fc63df3a06813567
parent c0aeff11f63d8de2cdf7bfc8f70df031f4775ef4
author Dave Borowitz <dborowitz@google.com> 1370886567 -0700
committer Dave Borowitz <dborowitz@google.com> 1370888800 -0700

Small optimizations to VisibilityCache

Short-circuit isVisibleFrom when no refs passed. Exclude heads and
tags from other refs, since those were already checked.

Change-Id: I5d5d0952a1db67c33ffc20df402f976946459137