Reduce the number of hash lookups in requiresCompositingForAnimation()

This reduces the number of calls to
AnimationControllerPrivate::RenderObjectAnimationMap::get made during
RenderLayerCompositor::requiresCompositingForAnimation from
3 to 1. As observed in http://crbug.com/261443, these hash lookups
can be expensive, accounting for as much as 1.5% of CPU time during
page load.

More specifically, rather than making three calls to
AnimationController::isRunningAnimationOnRenderer (one call for
each acceleratable CSS property), each of which involves a hash
lookup to find the renderer's list of animations, we now make a
single call to a new method that does a single lookup to find the
renderer's list of animations and then checks if any of these
involve acceleratable CSS properties.

BUG=261443

Review URL: https://chromiumcodereview.appspot.com/20756002

git-svn-id: svn://svn.chromium.org/blink/trunk@155284 bbb929c8-8fbe-4397-9dbb-9b2b20218538