fix unit tests in IE9

Author: yyx990803

test/unit/features/component/component-keep-alive.spec.js

@@ -1,6 +1,6 @@
 import Vue from 'vue'
 import injectStyles from '../transition/inject-styles'
-import { isIE9 } from 'web/util/index'
+import { isIE9 } from 'core/util/env'
 import { nextFrame } from 'web/runtime/transition-util'
 
 describe('Component keep-alive', () => {

test/unit/features/directives/model-text.spec.js

@@ -1,5 +1,5 @@
 import Vue from 'vue'
-import { isIE9, isAndroid } from 'web/util/index'
+import { isIE9, isAndroid } from 'core/util/env'
 
 describe('Directive v-model text', () => {
   it('should update value both ways', done => {

test/unit/features/transition/transition-group.spec.js

@@ -1,6 +1,6 @@
 import Vue from 'vue'
 import injectStyles from './inject-styles'
-import { isIE9 } from 'web/util/index'
+import { isIE9 } from 'core/util/env'
 import { nextFrame } from 'web/runtime/transition-util'
 
 if (!isIE9) {

test/unit/features/transition/transition-mode.spec.js

@@ -1,6 +1,6 @@
 import Vue from 'vue'
 import injectStyles from './inject-styles'
-import { isIE9 } from 'web/util/index'
+import { isIE9 } from 'core/util/env'
 import { nextFrame } from 'web/runtime/transition-util'
 
 if (!isIE9) {

test/unit/features/transition/transition.spec.js

@@ -1,6 +1,6 @@
 import Vue from 'vue'
 import injectStyles from './inject-styles'
-import { isIE9 } from 'web/util/index'
+import { isIE9 } from 'core/util/env'
 import { nextFrame } from 'web/runtime/transition-util'
 
 if (!isIE9) {