While it's nice to have a fixed chrome version it slows down the yarn install,
downloads a lot of things, and the chrome version depends on various
system packages so one needss to have chromium installed anyway.

This means developers that want to work on tests need firefox and chdomium installed.

Sadly I couldn't find a way to make browsers optional in case the developer
only has one installed.

Use tdd in all cases to be more consisstend.
Also since last year we can use chai with rollup directly, so
do that everywhere instead of relying on karma-chai injecting
it in to the global scope.