title: No prototype in qml js
body: <p>I have following code</p>
  
  <pre><code>function Model(onChanged) {
      this.array = new Array();
      this.onChanged = onChanged;
  }
  Model.prototype.push = function(val) {
      this.array.push(val);
      if (typeof(this.onChanged) !== 'undefined') {
          this.onChanged();
      }
  }
  
  console.log(JSON.stringify(Model.prototype));
  console.log(JSON.stringify(Model.prototype.push));
  </code></pre>
  
  <p>And this gives me</p>
  
  <pre><code>{}
  undefined
  </code></pre>
  
  <p>I've looked through some qml js code and there were same classes definitions so I can't get why this doesn't work for me. And autocomplete says that existing classes like Object, array, etc have prototype property. I tried to subclass them but got the same result.</p>