debugger: improve expansion behaviour of pinned tooltips.

Task-number: QTCREATORBUG-6554
Change-Id: I26ea4e5eb5826baaa6fd3bd4b199dd34e88703e0
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/debugger/gdb/gdbengine.cpp

@@ -3744,7 +3744,6 @@ bool GdbEngine::showToolTip()
         return false;
     }
     DebuggerToolTipWidget *tw = new DebuggerToolTipWidget;
-    tw->setDebuggerModel(TooltipsWatch);
     tw->setExpression(expression);
     tw->setContext(*m_toolTipContext);
     tw->acquireEngine(this);