[editing] Avoiding nesting like pre > p or p > h2 that works but aren't valid in html (#115)

With Chrome you can [end up](https://bugs.chromium.org/p/chromium/issues/detail?id=582020) with such nesting, not only they are not valid in HTML, but you can't un-nest the blocks.

Firefox maintains a low depth of blocks, I believe it's a good approach

There are no specs, but are what are the thoughts on this?

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/editing/issues/115