Update standards data in CanvasRenderingContext2D.json (#2553)
Update standards data in CanvasRenderingContext2D.json (#2553)

This property (back reference to the canvas creating the context) should be pretty standard and cross-browser compatible :)
- It's supported in all major browsers
- https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-canvas
mdn/browser-compat-data,teoli2003/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data