[FEAT] scheduleIntoFrame, an explicitly triggered requestAnimationFrame queue.

[runspired]

There is currently a flicker when prepending new items to a collection. This flicker occurs because wrapper components are inserted into the collection in a different frame from the one in which scrollTop is modified. To fix this, we need tighter control over frame scheduling.

scheduleIntoFrame gives you access to a frameQueue, similar in nature to backburner.schedule (Ember.run.schedule). This queue must be manually flushed, at which point it's work will all be performed in the nextFrame.

[runspired]

Closed in favor of setTimeout patch included in #60