title: Binding to array item works only once
body: <p>I am using <code>Angular 2.0.0-rc.5</code> and I have a component which looks like this:</p>
  
  <pre><code>@Component({
      ...
      template: `
      &lt;div *ngFor="let item of items; let i = index"
           [style.width]="getItemWeight(i)"&gt;
  
            &lt;!--
            Also I tried to bind it like this: [style.width]="(weights[i]*100)+'%'"
            But it binds only once anyway :-(
            --&gt;
  
          ...
      &lt;/div&gt;
      `
  })
  class MyComponent {
  
      private weights : number[] = [];
  
      @Input() items : any[] = [];
  
      /*
      Here I have some logic which alters this.weights (or even replaces it - I tried both ways).
      */
  
      private getItemWeight(index : number) : string {
          return `${this.weights[index] * 100}%`;
      }
  }
  </code></pre>
  
  <p>I have an <code>items</code> array and corresponding private <code>weights</code> array.
  All works good except binding to <code>weights</code> - it sets style once, but, for some reasons, not updates it when <code>weights</code> array altered or even replaced.</p>
  
  <p>Also I want to mention, that it is not connected with zones and so on - I tested it with simple string variable, which was declared in the same way and altered in the same place - all works perfectly with it and I presume that my problem connected with the fact that <code>weights</code> is array.</p>