Re-add extra hit-tests on GestureTap

In r178098 I removed 3 hit tests on GestureTap for the 3 derived mouse
events.  This broke a few websites in subtle ways.  This CL adds
explicit hit tests back while keeping the cleanup that gives us more
direct control over how mouse events are sent during a tap.  I'll be
taking a more sophisticated approach to eliminating these hit tests in
the common scenarios.

This also adds a number of new tests and updates the expectations for
a few tests.

BUG=396652, 397983, 398205

Review URL: https://codereview.chromium.org/429793004

git-svn-id: svn://svn.chromium.org/blink/trunk@179413 bbb929c8-8fbe-4397-9dbb-9b2b20218538