title: Typescript tsc compiler complaining about property not existing despite me updating lib.dom.t.ts
body: <p>I am trying to use webkitBackingStorePixelRatio on the HTML canvas.</p>
  
  <p>A statement like:</p>
  
  <pre><code>context.webkitBackingStorePixelRatio 
  </code></pre>
  
  <p>where context is the usual context of the HTML canvas, gives a type error in VSCode, as the webkitBackingStorePixelRatio property is not defined. I updated the CanvasRenderingContext2D interface in lib.dom.t.ts to this</p>
  
  <pre><code>interface CanvasRenderingContext2D extends CanvasCompositing, CanvasDrawImage, CanvasDrawPath, CanvasFillStrokeStyles, CanvasFilters, CanvasImageData, CanvasImageSmoothing, CanvasPath, CanvasPathDrawingStyles, CanvasRect, CanvasShadowStyles, CanvasState, CanvasText, CanvasTextDrawingStyles, CanvasTransform, CanvasUserInterface {
      mozBackingStorePixelRatio: any;
      msBackingStorePixelRatio: any;
      oBackingStorePixelRatio: any;
      backingStorePixelRatio: any;
      webkitBackingStorePixelRatio: any;
      readonly canvas: HTMLCanvasElement;
  }
  </code></pre>
  
  <p>Which resolves the VSCode error.</p>
  
  <p>However compiling using tsc still gives the same error <code>Property 'webkitBackingStorePixelRatio' does not exist on type 'CanvasRenderingContext2D'.</code></p>
  
  <p>Is there a way to force the tsc from command line to use lib.dom.d.ts the way VScode does so the error doesn't happen? Or is this inadvisable?</p>