This change also separates controlling visibility of "key preview
backing view" from suggestions strip visibility.
Bug: 5315001
Change-Id: I190a71f7956c804e5d89d2d5bacecc62d565ac2c
Previously tab key is shown only when the input type variant says that
it is web input. In addition to that, this change also shows tab key
when the IME option includes editor action (next and/or previous)
flag.
Bug: 3094312
Change-Id: I3f8841fdbcee918a0f93f3259090f24e70d96471
