CSS Regions: element has contentEditable attribute set and both it and a child of it are flowed in a the same region

Below you should see a rectangle with a black border with some text inside it. No red should be visible at any time during this test.
Click between the first pair of green and blue colored markers and type “foobar bazquux”
- The text you typed is displayed at the cursor position between the two markers and the lines of text wrap inside the black border
Click between the second pair of green and blue colored markers and type “foobar bazquux”
- The text you typed is displayed at the cursor position between the two markers and the lines of text wrap inside the black border

First line of editable content.

Likewise, this text between these colored markers should be editable.

This is some text that should be editable. Even the text between these two markers .