When the content after the current caret position consists only of whitespaces, double-pressing the enter key should break out of the list because spaces after the caret should not be considered content in the current list item.

Steps to reproduce:
1. Create a list
2. Type some text in the first line with a space after it
3. Move the cursor to the left before the space
4. Press enter twice
The current paragraph is still in a list.