Look out for maximum canvas size via supporting SVG plots

[fedarko]

TLDR: certain browsers (looking at you Chrome) impose maximum canvas size restrictions, which can lead to weird crashes (frustratingly, without any context). This is described at vega/vega-lite#4974.

It may be a good idea to somehow alert the user if the rank plot will contain, say, more than 30k features when in "ordinal" mode. Or switch to SVG somehow?

Just writing this down so that it's here for the future.