[GTK] Finetune captions menu as per design team
https://bugs.webkit.org/show_bug.cgi?id=129432

Reviewed by Eric Carlson.

Some design fine tuning of the captions dialog was required.

No new tests, current suffice.

* Modules/mediacontrols/mediaControlsApple.js:
Added out class.
* Modules/mediacontrols/mediaControlsGtk.js:
(ControllerGtk.prototype.buildCaptionMenu): Setting out class when
menu is going to show overlap the panel right border.
* css/mediaControlsGtk.css:
(video::-webkit-media-controls-closed-captions-container.out):
Setting all borders to 5px;
(video::-webkit-media-controls-closed-captions-container h3):
Reduced font size and increasing top padding.
(video::-webkit-media-controls-closed-captions-container ul):
Increased top padding.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@164857 268f45cc-cd09-0410-ab3c-d52691b4dbfc