refactor: remove polyfills (#1110)

BREAKING CHANGE: Remove polyfills from library

Author: eddyerburgh

Diff for: packages/test-utils/src/mount.js

@@ -1,7 +1,5 @@
 // @flow
 
-import './matches-polyfill'
-import './object-assign-polyfill'
 import Vue from 'vue'
 import VueWrapper from './vue-wrapper'
 import createInstance from 'create-instance'

Diff for: packages/test-utils/src/object-assign-polyfill.js

@@ -7,6 +7,7 @@ module.exports = function (config) {
     reporters: ['spec'],
     files: [
       '../../node_modules/babel-polyfill/dist/polyfill.js',
+      './polyfills.js',
       'load-tests.js'
     ],
     preprocessors: {

Diff for: test/setup/karma.conf.js

@@ -6,8 +6,8 @@ if (typeof Element !== 'undefined' && !Element.prototype.matches) {
     Element.prototype.oMatchesSelector ||
     Element.prototype.webkitMatchesSelector ||
     function (s) {
-      const matches = (this.document || this.ownerDocument).querySelectorAll(s)
-      let i = matches.length
+      var matches = (this.document || this.ownerDocument).querySelectorAll(s)
+      var i = matches.length
       while (--i >= 0 && matches.item(i) !== this) {}
       return i > -1
     }