This means that Browsh can now be entirely run just by running the CLI
binary. The client launches Firefox as a subprocess, then connects to it
via the Marionette protocol, installs the webextension and finally
triggers a new tab with, currently, the Google homepage in it.
I was trying to set this up for automated testing as well by installing
the built webextension as a temporary addon, because otherwise you need
to sign the extension everytime with a unique semantic version. However
for some reason I can't quite recreate the environment that MDN's
`web-ext` creates. The extension installs fine but fails to load the
`content.js` script, I can't find a backtrace or any other details about
the failure. So for now, we're just going to have to use `web-ext` as
seperate process and have the client connect to that. Which is what one
should do during development anyway, so it's not a huge loss.
This proves that frames can be generated on Firefox using the canvas and
a Tree Walker to examine text nodes. Already with little optimisation
frames don't ever take longer than 200ms to render.
Chrome has a MediaStream of the viewport, hopefully that will prove
performant as well.
This doesn't have functioning text colour detection or text occlusion
support. But early research suggests this will possible by comparing 2
screenshots: one with and the other without rendered text.
