Newly-added Large Text elements in Lists don't initially autosize correctly

Summary: Create a Property that is a List of Large Text. Add an element. Type multiple lines in it -- it doesn't resize the way that Large Text entry boxes should do.

The workaround is simply to save and go back into the Editor -- then the autosize code will work correctly.

Not sure what is going on here: the naive fix didn't work right, so this is going to require more investigation.