Fix direct share target cells's visibility

Due to incorrect initialization of the visibility status array, direct
share target cells were never truly set invisible (they were not visible
due to lack of content) and thus were iterated over by a keyboard
navigation. Because those “invisible” items overlapped with other,
visible, elements, it created an effect of a correct keyboard navigation
but incorrect target launching.

Fix: 244476932
Test: Manual testing, debugging.
Change-Id: Ic413948fea94aa6c658fad12fe81be2783b5f509