message: Guard against re-assigning read-only interaction event properties
diff: @@ -1768,8 +1768,8 @@ export default class InteractionManager extends EventEmitter
  if (typeof touch.pointerType === 'undefined') touch.pointerType = 'touch';
  if (typeof touch.pointerId === 'undefined') touch.pointerId = touch.identifier || 0;
  if (typeof touch.pressure === 'undefined') touch.pressure = touch.force || 0.5;
  - touch.twist = 0;
  - touch.tangentialPressure = 0;
  + if (typeof touch.twist === 'undefined') touch.twist = 0;
  + if (typeof touch.tangentialPressure === 'undefined') touch.tangentialPressure = 0;
  // TODO: Remove these, as layerX/Y is not a standard, is deprecated, has uneven
  // support, and the fill ins are not quite the same
  // offsetX/Y might be okay, but is not the same as clientX/Y when the canvas's top
  @@ -1794,8 +1794,8 @@ export default class InteractionManager extends EventEmitter
  if (typeof event.pointerType === 'undefined') event.pointerType = 'mouse';
  if (typeof event.pointerId === 'undefined') event.pointerId = MOUSE_POINTER_ID;
  if (typeof event.pressure === 'undefined') event.pressure = 0.5;
  - event.twist = 0;
  - event.tangentialPressure = 0;
  + if (typeof event.twist === 'undefined') event.twist = 0;
  + if (typeof event.tangentialPressure === 'undefined') event.tangentialPressure = 0;
  // mark the mouse event as normalized, just so that we know we did it
  event.isNormalized = true;
  