<textarea autoexpand> elements automatically expand to fit their content. There is a question of what to do when the textarea has initial content that extends beyond the boundaries of the element, before the user adds any new text to the element.

The current behavior prevents the autoexpand from happening in this case, and warns in the console. This PR requests that the element expand when the user focuses the element. There would be some sort of performant animation that shows the full content of the textarea, or expands to the max-height of the element.