Reply to thread

Steps to reproduce:

1. Open any thread.
2. Go to the reply form.
3. Insert -> Spoiler.
4. Press enter on a keyboard.

Result: spoiler is not inserted.

Expected: spoiler should be inserted without the title.

Workaround: click on the continue button, an empty spoiler will be inserted as expected.

Happens on the latest Google Chrome (both WIN and MAC).