upscaling an ImgBasedFont creates problems in the web ctx

[wkta]

In this project and this revision:
repo

If one doesn't disable the upscaling there is a display problem when converting to the web format
(text written using the pixelated font isn't displayed properly anymore).

On the other hand, if the text upscaling is disabled in shared.py then the display of pixelated text even in web context works OK.

See:

That problem is serious and requires urgent attention. The cause may be (again) due to how surfaces are handled via pyVM when using multiple temporary surfaces and/or subsurface operations… (->Cannot stack many operations)