title: Class properties are giving no-undef
body: <p>I'm trying to make a non-component class in ReactJS. Most tutorials I've followed on JavaScript show that when you're making a class, you can create properties simply by specifying them with <code>this.[name]</code>.</p>
  <p>Something really doesn't like this, and it throws me a <code>no-undef</code> error for my properties.</p>
  <p>Here is the code in question:</p>
  <pre class="lang-js prettyprint-override"><code>class MicroBitConnection {
      constructor(device) {
          this.device = device;
  
          this.connectDAP();
      }
  
      connectDAP() {
          this.transport = new DAPjs.WebUSB(device);
          this.dap       = new DAPjs.DAPLink(transport);
      }
  }
  </code></pre>
  <p>Right now I don't even instantiate the class anywhere, it gives me this error right off the bat:</p>
  <pre><code>Line 11:43:  'device' is not defined     no-undef
  Line 12:44:  'transport' is not defined  no-undef
  </code></pre>
  <p>It doesn't seem like a linting problem, because even with this warning off using <code>/* eslint no-undef: 0 */ // --&gt; OFF</code> at the top of the file, actually running the code with the class instantiated somewhere gives the same error:</p>
  <pre><code>Error: ReferenceError: device is not defined
  </code></pre>