fix standard rule upgrade

Author: yyx990803

.eslintrc

@@ -1,6 +1,7 @@
 {
   "extends": "standard",
   "rules": {
-    "arrow-parens": [2, "as-needed"]
+    "arrow-parens": [2, "as-needed"],
+    "no-duplicate-imports": 0
   }
 }

src/global-api.js

@@ -13,7 +13,7 @@ import * as transition from './transition/index'
 import FragmentFactory from './fragment/factory'
 import internalDirectives from './directives/internal/index'
 
-const {
+import {
   set,
   del,
   nextTick,
@@ -25,7 +25,7 @@ const {
   warn,
   isPlainObject,
   extend
-} = util
+} from './util/index'
 
 export default function (Vue) {
   /**