QmlObserver: Prevent messages from being sent if there is no server side

Actually this is fixed in QDeclarativeService::sendMessage, too, but the
fix won't be part of 4.7.1, so better double-check.

Reviewed-by: Christiaan Janssen

share/qtcreator/qml/qmljsdebugger/qdeclarativeobserverservice.cpp

@@ -236,4 +236,12 @@ QString QDeclarativeObserverService::idStringForObject(QObject *obj) const
     return idString;
 }
 
+void QDeclarativeObserverService::sendMessage(const QByteArray &message)
+{
+    if (status() != Enabled)
+        return;
+
+    QDeclarativeDebugService::sendMessage(message);
+}
+
 } // namespace QmlJSDebugger