Bug 880596 part 6 - Factor out common method for adding animations and transitions to a layer; r=dbaron
The loops for adding animations and transitions to a layer in
nsDisplayList::AddAnimationsAndTransitionsToLayer are now identical and so can
be factored out into a common method.
Since it is not possible to implicitly convert from
nsTArray<ElementPropertyTransition> to nsTArray<ElementAnimation> despite
ElementPropertyTransition being a subclass of ElementAnimation a templated
method is used. In the future, as animations and transitions share more and more
code, we should be able to remove the need for templates.