acquireContext(item) {
    // To prevent canvas fingerprinting, some add-ons undefine the getContext
    // method, for example: https://github.com/kkapsner/CanvasBlocker
    // https://github.com/chartjs/Chart.js/issues/2807
    return item && item.getContext && item.getContext('2d') || null;
  }
Platform class for charts without access to the DOM or to many element properties
This platform is used by default for any chart passed an OffscreenCanvas.
@extends BasePlatform