WIP: Be more detailed old chrome versions

[CrazyPython]

I'm opening this because as the owner of a real-world site that tried to use optional chaining, which is only supported in Chrome 79, two out of ten initial testers reported problems accessing the site until I stopped using the feature. While my case was likely an outlier, it illustrates how old browser versions are still in use because their auto-update has failed or for whatever reason.

Contributions welcome to this branch– feel free to send a pull request to my pull request.

• A new key for browser features not supported for >99% of users, but supported by their latest versions
• Colors fading based on percent of users that can use the feature
• Other ideas? @codestance