context重构

src/core/widget.js

@@ -338,7 +338,9 @@
                 throw new Error("name has already been existed");
             }
             widget._setParent && widget._setParent(this);
+            BI.Widget.pushContext(widget);
             widget._lazyConstructor();
+            BI.Widget.popContext();
             widget.on(BI.Events.DESTROY, function () {
                 BI.remove(self._children, this);
             });