feat: config中传下context

src/base/1.pane.js

@@ -41,7 +41,8 @@ BI.Pane = BI.inherit(BI.Widget, {
     loading: function () {
         var self = this, o = this.options;
         var loadingAnimation = BI.Providers.getProvider("bi.provider.system").getLoading({ 
-            loadingSize: o.loadingSize
+            loadingSize: o.loadingSize,
+            context: this
         });
         // pane在同步方式下由items决定tipText的显示与否
         // loading的异步情况下由loaded后对面板的populate的时机决定