title: Angular 4 @HostListener Window scroll event strangely does not work in Firefox
body: <p>I'm using <code>@HostListener('window:scroll', [])</code> in Angular 4 app in order to add additional class to the header on scrolling. It works fine in Chrome but I noticed that in Firefox 54.0 (I think it's the last current version) the class is not added, it does not execute onWindowScroll() method at all. What can be the reason?
  <br><br>
  Here is a part of the code and a <a href="https://embed.plnkr.co/i71NqvnkXMpfBxeFHhw3/" rel="noreferrer">Plunker Demo</a> (which by the way, also works fine in Chrome but not in Mozilla):<br></p>
  
  <pre><code>public isScrolled = false;
  constructor(@Inject(DOCUMENT) private document: any) {}
  @HostListener('window:scroll', [])
  onWindowScroll() {
      const number = this.document.body.scrollTop;
      if (number &gt; 150) {
          this.isScrolled = true;
      } else if (this.isScrolled &amp;&amp; number &lt; 10) {
          this.isScrolled = false;
      }
  }
  </code></pre>
  
  <p><br>
  Any help would be much appreciated.</p>