some preliminary work on the decoder code as per chris pearces' recommendations
Merge branch 'text-track-decoder' of git://github.com/ShayanZafar/mozilla-central into ttcue-zafar

Conflicts:
	content/html/content/src/HTMLTrackElement.cpp
	content/html/content/src/HTMLTrackElement.h
	content/html/content/src/WebVTTLoadListener.cpp
	content/html/content/src/WebVTTLoadListener.h