Pass modifier to mouse events for click/dblclick

A fix for the issue described here:

https://github.com/ariya/phantomjs/issues/11867
Adding tests for #11867

This tests mousedown, mouseup, click, and doubleclick for clicks with
modifier events. The mousedown/mouseup tests pass in 1.9.2, the
click/doubleclick do not. All pass with a build from this branch.
Merge pull request #11868 from bradleyboy/click-modifier-fix

Pass modifier to mouse events for click/dblclick