Canvas2d: Implement rerouting event by hit region's control.

According to the spec[1], should support rerouting event if there is a control
on hit region. This CL is also includes fixing two spec issues[2][3] and test.

[1] https://html.spec.whatwg.org/multipage/scripting.html#canvas-mouseevent-rerouting-steps
[2] https://github.com/whatwg/html/issues/547
[3] https://github.com/whatwg/html/issues/548

BUG=579076,579614,582792

Review URL: https://codereview.chromium.org/1654653002

Cr-Commit-Position: refs/heads/master@{#380870}
34 files changed