Refactor CE Surface to reduce event feedback

Restructure SurfaceObserver methods so that the method calls are more precise.

modules/ve/ce/ve.ce.SurfaceObserver.js
* Move timing code into startTimerLoop / stopTimerLoop / timerLoop
* Move poll logic into pollOnce

modules/ve/ce/ve.ce.Surface.js
modules/ve/ui/ve.ui.Surface.js
* Change all surfaceObserver calls to use new API

Change-Id: I0085e4a53c5a776733dce6944b867b8d2228ba4b
Merge "Refactor CE Surface to reduce event feedback"