Revert 124780 - Create a MediaSource object.

Revert 124780 - Create a MediaSource object.
https://bugs.webkit.org/show_bug.cgi?id=91773

Reviewed by Eric Carlson.

MediaSource object is needed in order to implement the new
object-oriented MediaSource API:
http://dvcs.w3.org/hg/html-media/raw-file/tip/media-source/media-source.html

No new tests - will be able to test after landing:
https://bugs.webkit.org/show_bug.cgi?id=91775

Adding new files to build files:
* CMakeLists.txt:
* DerivedSources.cpp:
* DerivedSources.make:
* DerivedSources.pri:
* GNUmakefile.list.am:
* Target.pri:
* WebCore.gypi:
* WebCore.vcproj/WebCore.vcproj:
* WebCore.xcodeproj/project.pbxproj:

New MediaSource object:
* Modules/mediasource/MediaSource.cpp: Added.
* Modules/mediasource/MediaSource.h: Added.
* Modules/mediasource/MediaSource.idl: Added.

Create a registry for the blob storage and lookup:
* Modules/mediasource/MediaSourceRegistry.cpp: Added.
* Modules/mediasource/MediaSourceRegistry.h: Added.

Connect SourceBuffer to MediaSource:
* Modules/mediasource/SourceBuffer.cpp:
(WebCore::SourceBuffer::SourceBuffer):
(WebCore::SourceBuffer::buffered): Forward call to MediaSource.
(WebCore::SourceBuffer::append): Ditto.
(WebCore::SourceBuffer::abort): Ditto.
* Modules/mediasource/SourceBuffer.h:
(WebCore::SourceBuffer::create): Add a MediaSource to the constructor.
(WebCore::SourceBuffer::clear): Clear the MediaSource.
(SourceBuffer):
* Modules/mediasource/SourceBufferList.cpp: include SourceBuffer.h
* Modules/mediasource/SourceBufferList.h:

Make MediaSource an EventTarget:
* dom/EventTarget.h:
(WebCore):
* dom/EventTargetFactory.in:

Enable creation of MediaSource object URL from JavaScript:
* html/DOMURL.cpp:
(WebCore):
(WebCore::DOMURL::createObjectURL):
* html/DOMURL.h:
(WebCore):
(DOMURL):
* html/DOMURL.idl:

New MediaSource constructor:
* page/DOMWindow.idl:

TBR=annacc@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=125646