New Composer: Round trip through editing is not consistent.

[michaelkaye]

Description

Round tripping through the composer and edit window is not consistent:

_italic_ -> *italic*

> quote ->

>
quote

***both*** -> *both* #! this has lost the bolding. -> #17610

While I understand that some of these are synonyms for each other, it's a bit confusing that the examples don't line up with how the composer re-renders text.

Steps to reproduce

Type this in the edit window per instructions in the reallysmalltext

Send this:

Edit it and get this?

Version information

• Platform: web

For the web app:

• Browser: Firefox 68
• OS: Linux
• URL: riot.im/develop

[ara4n]

related: #10722

[bwindels]

Upped prio after https://matrix.to/#/!bEWtlqtDwCLFIAKAcv:matrix.org/$uwwDIz3qJu6fEVwOnkGCzUuD8-i3opT0PYBEgV8gMxI?via=matrix.org&via=feneas.org&via=maunium.net

[MadLittleMods]

The orignal example just happens to work now _italic_ -> *italic* ✅ but the opposite doesn't *italic* -> _italic_ ❌

The > quote example is also still relevant.

The both italic and bold problem is separately being tracked by #17610 and was also reported in #11477