title: {"isTrusted":true} exception in core.umd.js
body: <p>I'm using Angular 2 and everything is working great in Chrome, but
  I started getting the following error in Firefox:</p>
  
  <blockquote>
    <p>EXCEPTION: 0 -  {"isTrusted":true} in   core.umd.js</p>
  </blockquote>
  
  <p>I have no idea what is causing this or where it is coming from, so I don't even know where to begin with debugging it. I did some Googling, but couldn't find anything useful. Here is an image of what I'm seeing in the console:</p>
  
  <p><a href="https://i.stack.imgur.com/oBor1.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/oBor1.jpg" alt="enter image description here"></a></p>
  
  <p>Does anyone have any idea what this means?</p>