Bug 987529 - Part 1: Integrate GeckoTouchDispatcher into vsync dispatcher

Add a new class, InputDispatcherRegistryHost, to handle the ticktask for
GeckoTouchDispatcher. In this patch, we also revise some data members
and member functions of other VsyncEventRegistries.

BTW, the input monitor is still under construction. We have to make sure
the waiting delay of each input event shouldn't longer than 4 ms.