title: svg element in pseudo content does not appear
body: <p>This problem has occurred in chrome version 51.0.2704.84.</p>
  
  <pre><code>.svg a:before {
      display: inline-block;
      width: 26px;
      height: 26px;
      content: url("link.svg");
  }
  </code></pre>
  
  <p>here is sample code.</p>
  
  <p><a href="https://webnobushi.github.io/svgbug/" rel="noreferrer">Reproduction page</a></p>
  
  <p><a href="https://github.com/webnobushi/svgbug/tree/master/dist" rel="noreferrer">Sample code</a></p>
  
  <p>Please tell me if there is a mistake .</p>
  
  <p>Work around: use the background url property,This problem could be avoided.</p>