Send got/lostpointercapture immediately if possible

After calls to set/releasepointercapture queue
the process pending pointer capture task if the
capture target and pending capture target were the
same. This way it not only sends the capture event
immediately in the normal cases but also doesn't
generate to the inifinite got/lostpointercapture
event sequence.

BUG=627192

Review-Url: https://codereview.chromium.org/2147263003
Cr-Commit-Position: refs/heads/master@{#406972}
10 files changed