title: No colon after property name in object declaration, is it valid?
body: <p>I entered this expression in the Firefox and Chrome Dev Console and I wonder why it is valid JavaScript:</p>
  
  <pre><code>var x = { a (b) {} };
  console.log(x);
  </code></pre>
  
  <p><code>x</code> is then set to an object with the property "a" containing a function called "a" with an argument identifier "b".
  How is this valid JavaScript syntax? The colon is missing after "a" and I do not understand the function definition.</p>