Bug 1026302 part 1 - Move IsForElement and PseudoElement from ElementAnimations to CommonElementAnimationData; r=dbaron

IsForElement and PseudoElement are currently only defined on ElementAnimations
but could be used for transitions. This patch moves these methods to the common
base class CommonElementAnimationData and also makes use of PseudoElement within
nsTransitionManager.
Bug 1026302 part 2 - Move PostRestyleForAnimation to CommonElementAnimationData; r=dbaron

This patch moves PostRestyleForAnimation from ElementAnimations to the base
class CommonElementAnimationData and makes use of it within nsTransitionManager.