title: ngx-infinite-scroll event not being triggered when scroll is complete
body: <p>I am trying to implement infinite scroll using ngx-infinite-scroll in an angular 4 app but it its not being triggered. I read the documents and set the <code>height</code> of the element and set <code>scrollWindow</code> to false so that its triggered when the element is scrolled and not the entire page. However I can't get it to fire.</p>
  
  <p>What am I doing worng?</p>
  
  <p>I've created a <a href="https://plnkr.co/edit/pyIFyBtRD9XfMpmsgc9C" rel="nofollow noreferrer">plnkr</a> to reproduce the issue</p>
  
  <p>html</p>
  
  <pre><code>&lt;div class="search-results"
       infinite-scroll
       [infiniteScrollDistance]="0.1"
       [infiniteScrollThrottle]="10"
       [scrollWindow]="false"
       (scrolled)="onScrollDown()"&gt;
    &lt;p *ngFor="let i of is"&gt;
      {{i}}
    &lt;/p&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>css</p>
  
  <pre><code>.search-results {
    height: 100px;
    overflow: scroll;
  }
  </code></pre>
  
  <p>component</p>
  
  <pre><code>protected is = ['Item1', 'Item2', 'Item3'];
  
  onScrolledDown() {
      console.log("scrolled");
  }
  </code></pre>