Try to watch local variable in watchwindow-DND, too.

Fix codepath overlooked in
6886e485de by introducing
a WatchHandler::watchVariable().

Task-number: QTCREATORBUG-8120
Change-Id: Ibab2619754e0006f3c81810a6bfdf758261c169e
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/debugger/watchhandler.h

@@ -77,6 +77,7 @@ public:
 
     void cleanup();
     void watchExpression(const QString &exp, const QString &name = QString());
+    void watchVariable(const QString &exp);
     Q_SLOT void clearWatches();
 
     void updateWatchers(); // Called after locals are fetched