our js firewalls (as I call LibreJS, NoScript, JShelter et al) should probably block and highlight such weirdnesses, but my advice in the article and lecture on spectre & meltdown get me wondering whether software with such tricks could possibly qualify as free software. with invisible characters, you can't really see the complete sources, can you? with misleading characters, what you (think you) see is not really what's there. whether or not it fits the free software definition, the advice that you shouldn't let into your computer software that doesn't serve you stands
https://www.fsfla.org/~lxoliva/#specmelt