[Build] use vue-cli to build site (#3734)

docs/site/utils/i18n.js

@@ -1,18 +0,0 @@
-// component mixin
-import { get } from '../../../src/utils';
-import { camelize } from '../../../src/utils/format/string';
-
-export default {
-  computed: {
-    $t() {
-      const { name } = this.$options;
-      const prefix = name ? camelize(name) + '.' : '';
-      const messages = this.$vantMessages[this.$vantLang];
-
-      return (path, ...args) => {
-        const message = get(messages, prefix + path) || get(messages, path);
-        return typeof message === 'function' ? message(...args) : message;
-      };
-    }
-  }
-};