The minimum browser versions have been updated to Chromium v80 and
Firefox v78.
Chromium v80 is >3 years old, and very few users use older versions
than that.
Firefox v78 is two extended support releases ago (v91 and v102 ar the
previous and current ESR releases).
Support has been restored for Chromium v78. Previously the extension
would crash upon startup.
The main incompatibility was the use of ES2020 operators (the optional
chain and nullish coalesce operators) in the libraries
`@ethereumjs/util` and `superstruct`. This was resolved by transpiling
those libraries.
After fixing that, the extension no longer crashed but the UI refused
to connect. This was because the UI process was not being identified as
an internal process, because the code responsible for checking that was
relying on the `origin` property of `MessageSender` [1] which wasn't
added until Chromium v80. The check has been updated to use the `url`
property instead, which existed in older versions of Chrome.
Lastly, the content security policy was updated to include the default
content security policy alongside the intended modification. Newer
versions of Chrome will merge the configired CSP with the default, but
older versions required it to be explicitly specified. This should not
result in any functional change.
[1]: https://developer.chrome.com/docs/extensions/reference/runtime/#type-MessageSender
Resolve an inconsistency between Chrome and Firefox with how the
contentscript runs in an iframe.
This should have no user-facing impact, it's just meant as a safeguard
in case something unintentionally gets included in the contentscript.
