Minor updates to captions menu UI
https://bugs.webkit.org/show_bug.cgi?id=109005

Reviewed by Eric Carlson.

Now that we only have a single section in the captions menu, remove the
unnecessary wrapper element. Also update the UI for Mac so that the menu
grows in size dynamically, and change the text we display for a caption
that has neither label or language identifiers.

Covered by existing tests.

* English.lproj/Localizable.strings: New string for an unknown caption label.
* css/fullscreenQuickTime.css: New rules for the captions menu.
(video:-webkit-full-screen::-webkit-media-controls-closed-captions-container):
(video:-webkit-full-screen::-webkit-media-controls-closed-captions-track-list):
* css/mediaControlsQuickTime.css: Ditto.
(video::-webkit-media-controls-closed-captions-container):
(video::-webkit-media-controls-closed-captions-track-list):
* html/shadow/MediaControlElements.cpp:
(WebCore::MediaControlClosedCaptionsTrackListElement::rebuildTrackListMenu):
    Remove the <section> element container.
* platform/LocalizedStrings.cpp:
(WebCore::textTrackNoLabelText): New string for an unknown caption label.

LayoutTests:

A caption track without a label or language is now given the menu
title 'Unknown'. Note also that the test includes some intentional
failure text.

* media/video-controls-captions-trackmenu-localized.html:
* platform/mac/media/video-controls-captions-trackmenu-localized-expected.txt:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@142003 268f45cc-cd09-0410-ab3c-d52691b4dbfc