Fix a bug with the 'add to dict' hint popping up too much

Not having a main dictionary is not sufficient reason to display
the hint. If the user already added the word to the dictionary then
we shouldn't be displaying it again, even if we don't have a main
dictionary for the current language.

Bug: 6829798
Change-Id: I6b081f51c82ef395fe2e394fd3167363e743ea6f