context重构

dist/fix/fix.compact.ie.js

@@ -33,7 +33,8 @@
     }
 
     function popTarget () {
-        Fix.Model.target = target = targetStack.pop();
+        targetStack.pop();
+        Fix.Model.target = target = null;
     }
 
     var oldWatch = Fix.watch;

dist/fix/fix.compact.js

@@ -33,7 +33,8 @@
     }
 
     function popTarget () {
-        Fix.Model.target = target = targetStack.pop();
+        targetStack.pop();
+        Fix.Model.target = target = null;
     }
 
     var oldWatch = Fix.watch;

src/core/widget.js

@@ -517,7 +517,8 @@
     };
 
     BI.Widget.popContext = function () {
-        BI.Widget.context = context = contextStack.pop();
+        contextStack.pop();
+        BI.Widget.context = context = null;
     };
 
     function pushTarget (_current) {
@@ -526,7 +527,8 @@
     }
 
     function popTarget () {
-        BI.Widget.current = current = currentStack.pop();
+        currentStack.pop();
+        BI.Widget.current = current = null;
     }
 
     BI.onBeforeMount = function (beforeMount) {