Fix typo.
The chroot browser library is meant to be used with `set -e`.
run_browser_in_chroot() is a better name.
Fix typo in function name.
Add missing negation.
Simplify regex by using grep's --extended-regexp.
Document wait_until(), and how the timeout isn't accurate.
Cleanup.

We have just create the ${browser_profile} dir, and we did not put any
of those files in there, so they cannot possibly exist.
Don't use -f with rm.

We rather see a fatal failure here e.g. if the file we want to remove
has moved.
Refactor some hardcoded paths into functions.
Use variable.
Merge set_chroot_torbutton_browser_name () into set_chroot_browser_name().
Name variables as "home page" instead of "start page".

So it's not confused with Tor Browser's default search eninge,
Startpage.
7z can now extract Mozilla's non-standard ZIP-compressed files without issue.
Refactor further, renaming a few functions (for clarity) along the way.
Reorder functions.
Remove unused variable.
Refactor another hardcoded path.
Don't suppress output to ease future debugging.

We still do it for `try_for()` blocks, since they quite quickly can
puke out screenfulls of errors.
Link to chroot browser library from the design pages.