Improve animation timing.

Detect when a vsync message was significantly delayed which may
indicate that a frame was skipped.  When this happens, update
the frame time to reflect the approximate start time of the
current frame instead of the start time of the frame that was
skipped a long time ago.

Removed an unnecessary call to getCurrentPlayTime() in the
animator framework.  The result was always zero and the call
just made the code confusing.

Bug: 6443611
Change-Id: I92b24f7ffd74c59b75a727b6bfc0bb51fc92a73a