title: Angular 4 cannot find name 'ViewChild'
body: <p>I have this strange error and didn't find anything similar to it ..
  I'm using ng2-canvas-whiteboard component for a drawing canvas on my website, everything's working perfectly except when i try to get reference to that canvas using : </p>
  
  <pre><code>@ViewChild('canvasWhiteboard') canvasWhiteboard: CanvasWhiteboardComponent;
  </code></pre>
  
  <p>as the official docs suggested, i'm getting this error : </p>
  
  <pre><code>Failed to compile.
  
  e:/frontend/src/app/components/user/dashboard/dashboard.component.ts (15,2): Cannot find name 'ViewChild'.
  </code></pre>
  
  <p>Any suggestions ? Thank you</p>