Surface::configure() should resize canvas

[daxpedda]

Is your feature request related to a problem? Please describe.
The problem is rust-windowing/winit#2733:

I am using transferControlToOffscreen() to draw in a different thread, which unfortunately invalidates any calls to width() and height().

While trying to figure out how this could be fixed in winit, I got the idea that maybe this shouldn't be winits problem after all. Setting the width and height of the canvas doesn't actually resize the canvas visually, it only resizes the surface the canvas is drawing on (the browser stretches or compresses the surface to fit the visual canvas size), which sounds like it would be the job of the renderer, not the window handler. Currently winit does both, changing the visual size of the canvas and it's surface.

Describe the solution you'd like
Surface::configure() gets passed the size anyway, it would then use width() and height() to resize the canvas as well.
This is what softbuffer does as well (src).

Describe alternatives you've considered
The alternative is to fix it in winit, which would require additional awareness by winit about what is done to the canvas to render to it.