Reviewed by Darin Adler.

        REGRESSION (r61285): some Dashboard widgets are always invisible due to
        HTML parser changes.
        https://bugs.webkit.org/show_bug.cgi?id=46435

        Enable pre-HTML5 parser quirks if Dashboard is in backward compatibility
        mode.

        * WebView/WebView.mm:
        (-[WebView _needsPreHTML5ParserQuirks]): Renamed from
        shouldUsePreHTML5ParserQuirks(). Return true if
        WebCore::Settings::usesDashboardCompatibilityMode() is true.
        (-[WebView _preferencesChangedNotification:]):
        (-[WebView _setDashboardBehavior:to:]): Enable pre-HTML5 parser quirks
        if Dashboard behavior is set to backward compatibility mode.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@68228 268f45cc-cd09-0410-ab3c-d52691b4dbfc