If you do `*` then space or `1. ` then space at the beginning of a line,
we automatically create a list. Now you can use undo to undo just the
automatic list creation, reverting to the plain text you typed.
The fixer node may get removed when merging adjacent inlines, so move
the cleanup to before this. For safety, also properly check for non-null
nodes so we don't crash if it's still elided for some reason.
There seems to be a bug in Chrome where it will sometimes not render
some of the text in the DOM when there are multiple zero-width spaces
around the beginning and ends of inline tags (not sure on the exact
details).
Steps to reproduce (prior to this commit):
1. Turn on bold and underlined text
2. Type something in bold and underlined text
3. Turn off bold and underline
4. Try to type something — it will not show up! That is, until you press
the enter key and we remove the zero-width spaces.
This is a massive refactor to port Squire to TypeScript, fix a bunch of small
bugs and modernise our tooling. The development was done on an internal
repository, so apologies to anyone following externally for the commit dump;
updates from here should come as real commits again.
Co-authored-by: Joe Woods <woods@fastmailteam.com>
