title: Height not being set on element using Angular 2 directive
body: <p>I'm trying to create a fluid textarea but I can't get the height to be set on the element when using "the angular 2 way" of doing DOM manipulation. </p>
  
  <p>Component:</p>
  
  <pre><code>import {Directive, ElementRef, HostBinding, HostListener} from '@angular/core';
  
  @Directive({
    selector: '[fluidHeight]',
    host: {
      '(input)': 'setHeight()'
    }
  })
  
  export class FluidHeightDirective {
  
    constructor(private _elementRef: ElementRef) {}
  
    @HostBinding('style.height.px')
    height: number;
  
    setHeight() {
      this.height = this._elementRef.nativeElement.scrollHeight + 'px';
    }
  }
  </code></pre>
  
  <p>Markup:</p>
  
  <pre><code>&lt;textarea [(ngModel)]="model" fluidHeight&gt;&lt;/textarea&gt;
  </code></pre>
  
  <p>Why is it that I get the correct value in the <code>setHeight</code> function but the height isn't being set on the <code>textarea</code>? </p>