Reviewed by Adam Barth.

        Suspend HTMLParserScheduler when page load is deferred to
        avoid potential JS re-entrancy. Otherwise, when JS execution is triggered
        from an external script or by events, and is blocked by a modal dialog,
        WebKit can parse more HTML source and also start another JS execution.

        https://bugs.webkit.org/show_bug.cgi?id=48077

        Test case: WebCore/manual-tests/bugzilla-48077.html.

        * dom/DocumentParser.cpp:
        (WebCore::DocumentParser::suspendScheduledTasks):
        (WebCore::DocumentParser::resumeScheduledTasks):
        * dom/DocumentParser.h:
        * html/parser/HTMLDocumentParser.cpp:
        (WebCore::HTMLDocumentParser::suspendScheduledTasks):
        (WebCore::HTMLDocumentParser::resumeScheduledTasks):
        * html/parser/HTMLParserScheduler.cpp:
        (WebCore::HTMLParserScheduler::HTMLParserScheduler):
        (WebCore::HTMLParserScheduler::suspend):
        (WebCore::HTMLParserScheduler::resume):
        * html/parser/HTMLParserScheduler.h:
        (WebCore::HTMLParserScheduler::isScheduledForResume):
        * page/PageGroupLoadDeferrer.cpp:
        (WebCore::PageGroupLoadDeferrer::PageGroupLoadDeferrer):
        (WebCore::PageGroupLoadDeferrer::~PageGroupLoadDeferrer):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@75066 268f45cc-cd09-0410-ab3c-d52691b4dbfc