Reviewed by Alexey Proskuryakov.

        WebSocket needs to suspend/resume as Active DOM object.
        https://bugs.webkit.org/show_bug.cgi?id=38171

        Implement suspend()/resume() in WebSocket and WebSocketChannel.
        While WebSocketChannel is suspended, it only adds received data in m_buffer
        or record the handle was closed, and report no event to WebSocket.
        When resumed, it will process buffer or handle closing.
        Since suspend/resume would be called while processing JavaScript event handler (e.g. before/after alert()), WebSocketChannel method that would fire an event need to be reentrant.
        So, WebSocketChannel::processBuffer() call WebSocket to fire an event at most once and skips buffer before the calling,
        so that next call of processBuffer() would process the next frame.

        * websockets/ThreadableWebSocketChannel.h:
        * websockets/ThreadableWebSocketChannelClientWrapper.h:
        (WebCore::ThreadableWebSocketChannelClientWrapper::didConnect):
          Mark channel is opened, and process pending events if not suspended.
        (WebCore::ThreadableWebSocketChannelClientWrapper::didReceiveMessage):
          Push message back in pending queue, and process pending events if not suspended.
        (WebCore::ThreadableWebSocketChannelClientWrapper::didClose):
          Mark channel is closed, and process pending events if not suspended.
        (WebCore::ThreadableWebSocketChannelClientWrapper::suspend):
          Mark suspended.
        (WebCore::ThreadableWebSocketChannelClientWrapper::resume):
          Unmark suspended, and process pending events.
        (WebCore::ThreadableWebSocketChannelClientWrapper::ThreadableWebSocketChannelClientWrapper):
        (WebCore::ThreadableWebSocketChannelClientWrapper::processPendingEvents):
        * websockets/WebSocket.cpp:
        (WebCore::WebSocket::canSuspend):
        (WebCore::WebSocket::suspend):
        (WebCore::WebSocket::resume):
        (WebCore::WebSocket::didClose):
        * websockets/WebSocket.h:
        * websockets/WebSocketChannel.cpp:
        (WebCore::WebSocketChannel::WebSocketChannel):
        (WebCore::WebSocketChannel::connect):
        (WebCore::WebSocketChannel::send):
        (WebCore::WebSocketChannel::bufferedAmount):
        (WebCore::WebSocketChannel::close):
        (WebCore::WebSocketChannel::suspend):
        (WebCore::WebSocketChannel::resume):
         When resumed, it will process buffer and
         handle closing if handle was already closed while suspended.
        (WebCore::WebSocketChannel::didClose):
         If suspended, record unhandled bufferedAmount and set m_closed true, so that closing will be processed when resumed.
        (WebCore::WebSocketChannel::didReceiveData):
         Add received data in buffer and process buffer while it is not suspended.
        (WebCore::WebSocketChannel::processBuffer):
         Process handshake header or one frame message.
         Return true if there are more data to be processed.
         Return false otherwise (e.g. incomplete handshake header or incomplete frame).
        * websockets/WebSocketChannel.h:
        * websockets/WorkerThreadableWebSocketChannel.cpp:
        (WebCore::WorkerThreadableWebSocketChannel::suspend):
        (WebCore::WorkerThreadableWebSocketChannel::resume):
        (WebCore::WorkerThreadableWebSocketChannel::Peer::suspend):
        (WebCore::WorkerThreadableWebSocketChannel::Peer::resume):
        (WebCore::WorkerThreadableWebSocketChannel::mainThreadSuspend):
        (WebCore::WorkerThreadableWebSocketChannel::Bridge::suspend):
        (WebCore::WorkerThreadableWebSocketChannel::mainThreadResume):
        (WebCore::WorkerThreadableWebSocketChannel::Bridge::resume):
        * websockets/WorkerThreadableWebSocketChannel.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@59116 268f45cc-cd09-0410-ab3c-d52691b4dbfc