Merge pull request #132 from mozilla/develop

only update _videoFrameCanvas if accessing video

polyfill/reality/CameraReality.js

@@ -132,9 +132,11 @@ export default class CameraReality extends Reality {
 			canvasHeight = this._videoRenderHeight = height;				
 			var cameraAspect = canvasWidth / canvasHeight;
 
+			if (this._videoFrameCanvas) {
 				this._videoFrameCanvas.width = width;
 				this._videoFrameCanvas.height = height;
 			}
+		}
 
 		this._setFovy(this._cameraFov / (Math.PI/180))