Revert 175644

Revert 175644
> Solution: the popup keeps mouse capture, so that any mouse click closes it (via WebKit's WebPopupMenuImpl.cpp) not just clicks in it or in its browser window.
> 
> BUG=161129
> TEST=navigate to
> http://www.w3schools.com/tags/tryit.asp?filename=tryhtml_select
> Click on the "car name" to bring up the pop-up.
> Click outside the browser window to see it close (just as for clicking inside the browser window)
> 
> 
> Review URL: https://chromiumcodereview.appspot.com/11675002

TBR=sschmitz@chromium.org
BUG=169115, 161129
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=175951