Reviewed by Brady.

        <rdar://problem/5931742> Support navigator.onLine from HTML5
        
        * WebCore.vcproj/WebCore.vcproj:
        * WebCore.xcodeproj/project.pbxproj:
        Add NetworkStateNotifier files.
        
        * dom/EventNames.h:
        Add offline and online events.
        
        * page/Navigator.cpp:
        (WebCore::Navigator::onLine):
        * page/Navigator.h:
        * page/Navigator.idl:
        Add navigator.onLine.
        
        * page/Page.cpp:
        (WebCore::networkStateChanged):
        Dispatch offline/online events to all frames.
        
        (WebCore::Page::Page):
        Set state change callback.
        
        * platform/network/NetworkStateNotifier.cpp: Added.
        * platform/network/NetworkStateNotifier.h: Added.

        * platform/network/mac/NetworkStateNotifierMac.cpp: Added.
        Mac network state notifier.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@33457 268f45cc-cd09-0410-ab3c-d52691b4dbfc