title: Imported class cannot be used as service in Angular.js with TypeScript
body: <p>I'm converting an ES6 project to TypeScript and I've encountered an issue when using <code>@typed/angular</code> with the <code>.service</code> call in Angular.js.</p>
  
  <p>If I do this:</p>
  
  <pre><code>import * as angular from 'angular';
  class OrderTreeService {}
  
  export const orderTree = angular
      .module('orderTree', [])
      .service('OrderTreeService', OrderTreeService)
      .name;
  </code></pre>
  
  <p>It works perfectly.
  However, if I move that service to a file <code>order-service.service.ts</code> and do this:</p>
  
  <pre><code>import * as angular from 'angular';
  import { OrderTreeService } from './order-tree.service';
  
  export const orderTree = angular
      .module('orderTree', [])
      .service('OrderTreeService', OrderTreeService)
      .name;
  </code></pre>
  
  <p>Then it no longer worked and has this error:</p>
  
  <pre><code>TS2345: Argument of type 'typeof OrderTreeService' is not assignable to parameter of type 'Injectable&lt;Function&gt;'.
    Type 'typeof OrderTreeService' is not assignable to type '(string | Function)[]'.
      Property 'pop' is missing in type 'typeof OrderTreeService'.
  </code></pre>
  
  <p>I can't figure out what the difference is? Is it losing some type information somewhere along the way?</p>
  
  <p>This is the contents of <code>order-service.service.ts</code>:</p>
  
  <pre><code>export class OrderTreeService {}
  </code></pre>