Don't call resetDictionaries if DictionaryFacilitatorLruCache.get()

hasn't been called yet. This breaks the AOSP SpellChecker.  This seems
to be a bug introduced recently, when the
DictionaryFacilitatorLruCache was turned into a "cache" of 1 element.

Change-Id: I55f6c18b274c9a33fd62cb25bcd02f64788d5ff0