Stop generating frames when the animation is complete
Stop generating frames when all players are paused
Teach new framework about Firefox.
Merge pull request #150 from dstockwell/raf-scheduling

Stop generating frames when the animation is complete
Merge pull request #151 from shans/ff-support-for-new-framework

Teach new framework about Firefox.
Add testharness.js as a submodule
Merge pull request #152 from dstockwell/test-harness

Add testharness.js as a submodule
Remove arguments from TimedItem._isCurrentDirectionForwards()
Clarify TimedItem._isPastEndOfActiveInterval()

No functional change
Initial implementation of media integration