Don't check description validity on keyup

For really long descriptions, I think especially with fast typists, and
on slow computers, this may cause issues. We don't need validity checked
until the end, anyway, and this preserves the onblur check.

Bug: 33607
Change-Id: I6244371bd864cd6d4cbf8cbbfad122d1f0e68ef8
Merge "Don't check description validity on keyup"