title: Invalid CSS property value for background with image and extension gradient
body: <p>Chrome has started to warn me about my legacy gradients:</p>
  
  <pre><code>Invalid CSS property value: right no-repeat url('../Images/Logo_white.png'), 
  -moz-linear-gradient(bottom, #899fa6, #3e545c) 
  </code></pre>
  
  <p>It is only for the extensions for o, moz and ms:</p>
  
  <pre><code>background: right no-repeat url('../Images/CompanyLogo.png'), 
  -moz-linear-gradient(bottom, #000000, #ffffff);
  </code></pre>
  
  <p>The one for webkit is fine:</p>
  
  <pre><code>background: right no-repeat url('../Images/CompanyLogo.png'), 
  -webkit-linear-gradient(bottom, #000000, #ffffff);
  </code></pre>
  
  <p>Am I doing something wrong?</p>
  
  <p>The extension-gradients do not generate a warning when they are used alone as opposed to being combined with an image.</p>