https://bugs.webkit.org/show_bug.cgi?id=88187

Implemented support for timestamps within a TextTrackCue.
This enables rendering functionality for Karaoke and Paint-on captions.

Patch by Victor Carbune <victor@rosedu.org> on 2012-06-09
Reviewed by Eric Carlson.

Source/WebCore:

Test: media/track/track-cue-rendering-inner-timestamps.html

* css/mediaControls.css: Remove the background shadow pseudo-id and
added two others, which can be further used for styling past / future
contents of the cue.
(video::-webkit-media-text-track-past-nodes): Used to style elements
within the cue that are before the current movie time.
(video::-webkit-media-text-track-future-nodes): Used to style elements
within the cue that are after the current movie time.
* html/HTMLMediaElement.cpp:
(WebCore::HTMLMediaElement::updateActiveTextTrackCues): Regardless of whether
the active set changed or not, the current cues need to be informed of the current
movie time.
* html/track/TextTrackCue.cpp:
(WebCore::TextTrackCue::TextTrackCue): Initiliazed past and future containers.
(WebCore::TextTrackCue::getCueAsHTML): Checked whether the current cue text has
inner timestamps or not, in order to render faster if no timestamps are there.
(WebCore::TextTrackCue::updateDisplayTree): Added method that keeps the past and future
containers up to date, given a current movie time.
(WebCore):
(WebCore::TextTrackCue::getDisplayTree): Replaced the cue background container with the
past cues container. The *internal* display tree of the cue now has two containers,
representing past and future elements.
* html/track/TextTrackCue.h: Added several variables to support the new functionality.
(TextTrackCue):
* html/track/WebVTTParser.cpp:
(WebCore::WebVTTParser::constructTreeFromToken): Updated representation for this patch.
* html/track/WebVTTParser.h:
(WebVTTParser): Made public the collectTimeStamp method, as this is required for
parsing timestamps within a cue as well.

LayoutTests:

* media/track/captions-webvtt/captions-inner-timestamps.vtt: Added.
* media/track/track-cue-rendering-inner-timestamps-expected.txt: Added.
* media/track/track-cue-rendering-inner-timestamps.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@119907 268f45cc-cd09-0410-ab3c-d52691b4dbfc