Unable to split formatted single element multiline quote

[Poldraunic]

Hi! Encountered an issue today.

Repro:

1. editor.setHTML('<i>foo<br>bar</i>'); editor.increaseQuoteLevel().
2. Set cursor to the end of the first line.
3. Press Enter. Get an empty line as expected.
4. Press Enter. Get another empty line instead of split.

isEmptyBlock() function checks the textContent property for an element. And in this case, it is not empty and so no split happens.

This example is a reduction of a real world E-mail I have in my database. Should I be doing some extra preprocessing for this kind of input? Is it possible to fix this in Squire itself?