main thread.
https://bugs.webkit.org/show_bug.cgi?id=43874

Reviewed by David Levin.

* Android.mk:
* CMakeLists.txt:
* GNUmakefile.am:
* WebCore.gypi:
* WebCore.pro:
* WebCore.vcproj/WebCore.vcproj:
* WebCore.xcodeproj/project.pbxproj:
* dom/ScriptExecutionContext.cpp:
(WebCore::ScriptExecutionContext::~ScriptExecutionContext):
(WebCore::ScriptExecutionContext::addBlob):
(WebCore::ScriptExecutionContext::removeBlob):
(WebCore::ScriptExecutionContext::createPublicBlobURL):
(WebCore::ScriptExecutionContext::revokePublicBlobURL):
* dom/ScriptExecutionContext.h:
* html/Blob.cpp:
(WebCore::Blob::Blob):
(WebCore::Blob::~Blob):
(WebCore::Blob::contextDestroyed):
* html/Blob.h:
* html/BlobRegistryImpl.cpp:
(WebCore::BlobRegistryImpl::registerBlobURL):
(WebCore::BlobRegistryImpl::unregisterBlobURL):
(WebCore::BlobRegistryImpl::getBlobDataFromURL):
* html/ThreadableBlobRegistry.cpp: Added.
* html/ThreadableBlobRegistry.h: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@65271 268f45cc-cd09-0410-ab3c-d52691b4dbfc