title: Using `console.log` inside of a Worker in Chrome prints the same message twice
body: <p>Pretty much what the title says. What is weirder is that this only happens when you run the program in a new tab, if you merely refresh the page, there will be only one message for each <code>console.log</code>.  </p>
  
  <p>Here is <code>main.js</code>: </p>
  
  <pre><code>const worker = new Worker('worker.js');
  </code></pre>
  
  <p>Here is <code>worker.js</code>:</p>
  
  <pre><code>console.log('Foo bar!');
  </code></pre>
  
  <p>Here is <code>index.html</code>:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;meta charset="UTF-8" /&gt;
  &lt;title&gt;Web Workers&lt;/title&gt;
  
  &lt;style&gt;&lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
  
  &lt;script src="main.js"&gt;&lt;/script&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>The same is not happening in Firefox. I am using Chrome version 65, what's more odd is that the duplicate message seems to belong to no contexts listed in the "contexts" dropdown, so the only message listed when I try to filter out all console messages aside from ones sent by <code>worker.js</code> is the first message, the second message (the duplicate) seems to belong to no contexts.</p>
  
  <p>@bean's answer revealed that there is already a question like this asked (from February 2018, I believe) which has not been answered. If no one answers this question either, I will consider raising an issue in Chrome's development forum/whatever.</p>