title: Registration of backend webgl failed for tensorflowjs
body: <p>As suggested in tensorflowjs github, I post the question here. I am getting below error, in simplest example possible with tensorflow. </p>
  
  <p><strong>Error:</strong><br>
  <a href="https://i.stack.imgur.com/3Bh63.png" rel="noreferrer"><img src="https://i.stack.imgur.com/3Bh63.png" alt="enter image description here"></a></p>
  
  <p><strong>Code:</strong>  A simple html snippet with just tfjs loading. </p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  &lt;head&gt;
      &lt;meta charset="UTF-8"&gt;
      &lt;meta name="viewport" content="width=device-width, initial-scale=1.0"&gt;
      &lt;meta http-equiv="X-UA-Compatible" content="ie=edge"&gt;
      &lt;script src="https://cdn.jsdelivr.net/npm/@tensorflow/tfjs@0.15.3/dist/tf.min.js"&gt;&lt;/script&gt;
      &lt;title&gt;Testing Tfjs&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;h2&gt;Testing Tfjs&lt;/h2&gt;    
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Browser: Chrome Version 72.0.3626.119<br>
  OS: Win 10, GPU: GT 740M, version 397.44.<br>
  Chrome gpu show says : (because I disabled hw acceleration to avoid chrome blacking out at times)</p>
  
  <pre><code>WebGL: Software only, hardware acceleration unavailable, 
  WebGL2: Software only, hardware acceleration unavailable
  </code></pre>
  
  <p>I have tried setting backend explicitly as cpu but it did not help. I have seen other posts in github talking about this error, but in vain.</p>