BI-88584 reafctor：代码优化

src/base/1.pane.js

@@ -139,6 +139,7 @@ BI.Pane = BI.inherit(BI.Widget, {
     },
 
     setTipText: function (text) {
+        this._assertTip();
         this._tipText.setText(text);
     },
 

src/case/layer/pane.list.js

@@ -123,7 +123,7 @@ BI.ListPane = BI.inherit(BI.Pane, {
         }
         BI.ListPane.superclass.populate.apply(this, arguments);
         var tipText = BI.get(arguments, [2], '');
-        BI.isNotEmptyString(tipText) && BI.ListPane.superclass.setTipText.apply(this, [tipText]);
+        BI.isNotEmptyString(tipText) && this.setTipText(tipText);
         this.button_group.populate.apply(this.button_group, arguments);
     },