Enter key
Test the Enter key support.
Notes:
- Expected behavior:
- At the end of a heading should create a new paragraph.
- In the middle of a heading should split it.
- Shift+Enter should move the text to new line.
- The selection should always be moved to the newly created block.
- Select all + Enter should leave an empty paragraph.
- Check:
- Non-collapsed selections.
- Integration with undo.
Integration with basic styles (bug).