Note AudioSinkWrapper can now report correct playback position when the media is video-only or audio-only.
We will handle the case where audio ends before video in next patch where it needs to switch to system clock when audio reaches the end.
The patch removes 455 occurrences of FAIL_ON_WARNINGS from moz.build files, and
adds 78 instances of ALLOW_COMPILER_WARNINGS. About half of those 78 are in
code we control and which should be removable with a little effort.
--HG--
extra : rebase_source : 82e3387abfbd5f1471e953961d301d3d97ed2973