highlighting list in quote

[cben]

> Foo
>
> 1. bar
> 2. baz

is not highlighted like a list. Changing the blank line from > to really blank fixes the 1. but not the 2..

[cben]

Reproduced & reported upstream: codemirror/codemirror5#3510
(why did I wait? was that so hard? maybe I wanted to fix it myself — not sure when I'll get to it but anyway better to report)