QmlV8DebuggerClient: Changes related to v8DebugService protocol

V8DebugService uses a different protocol. This fix now uses the
new protocol. It also optimizes the number of debug requests made
to retrieve debug information.

Change-Id: I40d7b1d4ab0535831c6a19cadd9b48763934c1de
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>

src/plugins/debugger/qml/qmldebuggerclient.h

@@ -92,6 +92,9 @@ protected:
     virtual void statusChanged(Status status);
     void sendMessage(const QByteArray &msg);
 
+    QList<QByteArray> cachedMessages();
+    void clearCachedMessages();
+
 private:
     QmlDebuggerClientPrivate *d;
     friend class QmlDebuggerClientPrivate;