Mac: Send a synthetic mouseup event when <select> popup menu is opened.

Mac: Send a synthetic mouseup event when <select> popup menu is opened.

On Mac, 'mouseup' and 'click' events were not dispatched when <select> popup
menu was opened because a popup menu is opened by a mousedown event, the menu is
overlaped on the host <select>, and mouseup event is not routed to the page.
This behaivor made some compatibility problems.

We make a synthetic mouseup event in this case.  Blink core dipatches 'mosueup'
and 'click' events for it. This workaround is very similar to one in Mac Safari.

BUG=36518
R=morrita@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=164215

[tkent, 2013-12-20 04:34:55]

Morita-san, can you review this?

[Hajime Morrita, 2013-12-20 05:17:43]

lgtm.

[commit-bot: I haz the power, 2013-12-20 05:19:06]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tkent@chromium.org/118453006/1

[commit-bot: I haz the power, 2013-12-20 07:31:16]

Change committed as 164215