Rename Regiser/Unregister and revise the function arguments

1. Register()   -> AddObserver()
2. Unregister() -> RemoveObserver()
3. Use two observer lists and observer pointers to handle always/non-always
   trigger case
Bug 987529 - Part 1: Integrate GeckoTouchDispatcher into vsyncdispatcher

For inputdispatcher, we should always trigger it, so we call
AddObserver() only once for each multitouch sequence.
Bug 987529 - part 2: Integrate refresh driver into vsync dispatcher

Integrate refresh drivers on Chrome/Content process into the
vsync dispatcher.
Bug 987529 - part 3: Integrate CompositorParent into vsync dispatcher

Call AddObserver() while we want to schedule the composition. We use
non-always triggered AddObserver() for CompositorParent.
systrace label for silk

add vsync trace timer

fix __LINE__ macro expend

fix print statistic function error