Bug 1288329: [ogg] P8. Enable new OggDemuxer by default. r=gerald

Now passes all media mochitests.

MozReview-Commit-ID: 85aVXrrRSWW

--HG--
extra : rebase_source : 3b7072a690914c31226186fada08ed978ff55b00

modules/libpref/init/all.js

@@ -544,7 +544,7 @@ pref("media.mediasource.webm.enabled", true);
 pref("media.mediasource.webm.audio.enabled", true);
 
 // Use new MediaFormatReader architecture for plain ogg.
-pref("media.format-reader.ogg", false);
+pref("media.format-reader.ogg", true);
 
 pref("media.benchmark.vp9.threshold", 150);
 pref("media.benchmark.frames", 300);