Use the real Task objects in BackgroundHTMLParser and make them cancelable
Merge branch 'parser' of github.com:tonygentilcore/webkit into parser

Conflicts:
	Source/WebCore/html/parser/BackgroundHTMLParser.h
	Source/WebCore/html/parser/HTMLDocumentParser.cpp
Merge branch 'parser' of github.com:tonygentilcore/webkit into parser