TextTrackRegion Constructor
https://bugs.webkit.org/show_bug.cgi?id=110511

Reviewed by Adam Barth.

Source/WebCore:

This is an initial patch for implementing the TextTrackRegion
defined in the "WebVTT Extension: Regions for rendering cue groups":
https://dvcs.w3.org/hg/text-tracks/raw-file/default/608toVTT/region.html

The feature components are hidden behind the WEBVTT_REGIONS flag
and is currently disabled by default in all ports and tests skipped.

Test: media/track/regions-webvtt/text-track-region-constructor.html

* WebCore.gypi: Added files to be included for building Chromium with
feature enabled (it is disabled by default).
* html/track/TextTrackRegion.cpp: Added.
(WebCore):
(WebCore::TextTrackRegion::TextTrackRegion):
(WebCore::TextTrackRegion::~TextTrackRegion):
(WebCore::TextTrackRegion::setId): Setter.
(WebCore::TextTrackRegion::setWidth): Setter.
(WebCore::TextTrackRegion::setHeight): Setter.
(WebCore::TextTrackRegion::setRegionAnchorX): Setter.
(WebCore::TextTrackRegion::setRegionAnchorY): Setter.
(WebCore::TextTrackRegion::setViewportAnchorX): Setter.
(WebCore::TextTrackRegion::setViewportAnchorY): Setter.
(WebCore::TextTrackRegion::scroll): Getter. Internally, the scroll
value is stored as a boolean, but when returned is converted to either
the empty string or "up".
(WebCore::TextTrackRegion::setScroll): Setter.
(WebCore::TextTrackRegion::setRegionSettings): Not used yet (see b/109818)
* html/track/TextTrackRegion.h: Added.
(WebCore):
(TextTrackRegion):
(WebCore::TextTrackRegion::create):
(WebCore::TextTrackRegion::track): Getter.
(WebCore::TextTrackRegion::id): Getter.
(WebCore::TextTrackRegion::width): Getter.
(WebCore::TextTrackRegion::height): Getter.
(WebCore::TextTrackRegion::regionAnchorX): Getter.
(WebCore::TextTrackRegion::regionAnchorY): Getter.
(WebCore::TextTrackRegion::viewportAnchorX): Getter.
(WebCore::TextTrackRegion::viewportAnchorY): Getter.
(WebCore::TextTrackRegion::regionSettings): Getter, used only internally (see b/109818).
* html/track/TextTrackRegion.idl: Added.
* page/DOMWindow.idl: Constructor support.

LayoutTests:

* TestExpectations:
* media/track/regions-webvtt/text-track-region-constructor-expected.txt: Added.
* media/track/regions-webvtt/text-track-region-constructor.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145053 268f45cc-cd09-0410-ab3c-d52691b4dbfc