Typing into an annotation next to a word break keeps annotation

Logic was failing because we were passing the index of the annotation
within the AnnotationSet, instead of the index within the Store, to
containsIndex().

Bug: 54332
Change-Id: Ibfd9abe6e4b44d9db744e0c5019418eee12f84a4
Merge "Typing into an annotation next to a word break keeps annotation"