babel-polyfill 兼容性优化

<p>1、安装<code>babel-polyfill</code>:</p> <pre><code>npm install --save babel-polyfill #yarn add babel-polyfill</code></pre> <p>2、修改<code>webpack.base.conf.js</code>文件下入口：</p> <pre><code> entry: { app: ['babel-polyfill', './src/main.js'], },</code></pre>