Don't use PostTask queueing between compositor and main thread.
Instead put the events in the main thread event queue where they can
be coalesced. This improves the latency on mouse move events ~5-7X
On Linux loading https://jsfiddle.net/va5vpxLz/6/
and getting ~250 mouse samples
Stable (RAF)
53.579747191011386
Stable (setTimeout)
27.226215139442306
With Change (RAF)
7.244861660078827
With Change (setTimeout)
5.327854330708663
BUG=624012,599152
Review-Url: https://codereview.chromium.org/2162143002
Cr-Commit-Position: refs/heads/master@{#410487}
15 files changed
