Bug 851338 - Implement AudioContext.currentTime; r=roc

Landed on a CLOSED TREE, because I'm mad at X11!
Back out 0044e4c2dc53 (bug 851149), 3080f18ba53d (bug 698328), 0b147c3f682b (bug 850713) for Android bustage
CLOSED TREE
Back out 298a598dde74 (bug 849988) for test_bug_779982.html timeouts
CLOSED TREE
Bug 837011 - CallCompiler should return 'true' because it doesn't throw an exception (r=dvander)

--HG--
extra : rebase_source : 326ad9707d64db437d0a7dddfef9bbffbb59038e
Bug 702504 - Make USE_WIDGET_LAYERS disabled a test failure. r=roc
Bug 676746 - Forcibly initialize the persistant layer manager when we try to read its backend type. r=joe
Bug 841651: Update NSPR to NSPR_4_9_6_RTM. Remove the private patch.