[RTE] Backspacing through an embedded form doesn't select/delete the form, and loses keyboard focus of RTE

[timriley]

In this GIF, I select/backspace through some text underneath an embedded form. When I get through the text, I try and continue to backspace, but instead of the embedded form being selected or deleted, the keyboard focus on the rich text editor is totally lost, and then if I proceed to hit up/down arrow keys, it moves the entire webpage rather than moving the cursor around the rich text editor.