Migration to Input Events Level 2

[Andrew-Chen-Wang]

Due to the deprecation of execCommand, we need a plan to migrate to Input Events Level 2.

This affects all repositories using the current Wasabeef original JS files. Several WSYIWYG editors use execCommand, and many are hesitant to actually migrate yet due to input events not being finalized yet. Because I'm kinda busy, I'm looking for any helpers to get started in case execCommand is suddenly dropped from Safari breaking anyone who upgrades their iOS.

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I mentioned this in the Android sister repo awhile ago, but no response. We're on our own :P Edit: I see why now too, ish:

from the main GitHub repo from W3 https://github.com/w3c/input-events/

Level 1 has two implementations (Chrome and Safari) and level 2 has one (Safari). Level 2 corresponds to the consensus reached within the Editing Taskforce at the end of 2016. Level 1 is a subset that was split off in early 2017, when the Chromium team announced that it would not implement the entire specifition. At this time Safari had already implemented the full specification. We also did not want to give up level 2 of the spec, because it actually resolves a lot of issues and there has been no counter-proposal to effectively solve these issues from the Android team or others. Given that Chromium team told the Editing Taskforce that it either had to release a spec with their proposed changes or they would drop the spec entirely, it was decided to split the specification in two levels.

In other words, our implementations will also be somewhat different.