This class contains a bunch of Gecko DOM specific stuff, and it would make
keeping the copy of MediaDecoder in Servo up to date easier if the Gecko
DOM stuff wasn't in MediaDecoder (and the other classes we import).
MozReview-Commit-ID: 3dP1nrQ7sT3
--HG--
extra : rebase_source : 79040a8d3cff6ac946b20a99d68e57630ec60848
Chris Pearce