QmlDesigner: Delete all bindings to deleted node

When a node is deleted we should remove all bindings to that node.

Change-Id: I3a6c3387c535ac8c79bfc83671614ed8abd246a5
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/designercore/model/qmlobjectnode.cpp

@@ -388,6 +388,8 @@ void QmlObjectNode::destroy()
     }
 
     removeStateOperationsForChildren(modelNode());
+    BindingProperty::deleteAllReferencesTo(modelNode());
+
     QmlFlowViewNode root(view()->rootModelNode());
 
     modelNode().destroy();