Add a flushing mechanism for the WebVTTParser
https://bugs.webkit.org/show_bug.cgi?id=130532

Reviewed by Eric Carlson.

Merged from Blink (patch by vcarbune@chromium.org):
https://chromium.googlesource.com/chromium/blink/+/1ac2b3081492ab8661429230004013a9a3623f0f
http://crbug.com/54203003
https://chromium.googlesource.com/chromium/blink/+/24343d32bc36d20d59ef3e10040faddde65929e6
http://crbug.com/59453002
https://chromium.googlesource.com/chromium/blink/+/ef2793f1d9d207389589ecf9a136ea5c7170b4af
http://crbug.com/75233002
https://chromium.googlesource.com/chromium/blink/+/a29f2f8324abcd4826b41e7dc34373dee2ec57a9
http://crbug.com/52713005
https://chromium.googlesource.com/chromium/blink/+/7ce003c8d47b39f116f1f2a592a5dfb4a9e77228
http://crbug.com/64303004
https://chromium.googlesource.com/chromium/blink/+/18f896b3498478311e880f782813d5dfc8c0c7d1
http://crbug.com/96933004
https://chromium.googlesource.com/chromium/blink/+/8670e8ecb13254a651f5493ec83f4484d18c154e
http://crbug.com/98783005
https://chromium.googlesource.com/chromium/blink/+/4ac55780a6af3d76e0159c1d145330964ad56647
http://crbug.com/104713002

Tests: http/tests/media/track/track-webvtt-slow-loading-2.html
       http/tests/media/track/track-webvtt-slow-loading.html

* CMakeLists.txt:
* GNUmakefile.list.am:
* WebCore.vcxproj/WebCore.vcxproj:
* WebCore.vcxproj/WebCore.vcxproj.filters:
* WebCore.xcodeproj/project.pbxproj:
* html/track/BufferedLineReader.cpp: Added.
* html/track/BufferedLineReader.h: Added.
* html/track/TextTrackRegion.cpp:
* html/track/VTTCue.cpp:
* html/track/WebVTTParser.cpp:
* html/track/WebVTTParser.h:
* loader/TextTrackLoader.cpp:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@165997 268f45cc-cd09-0410-ab3c-d52691b4dbfc
13 files changed