Takes the next activation ticket and returns it.
Same pre-increment contract as _nextStyleGeneration: the caller keeps the value its own request owns and later compares it against the counter to learn that a newer request has superseded it.
Takes the next activation ticket and returns it.
Same pre-increment contract as _nextStyleGeneration: the caller keeps the value its own request owns and later compares it against the counter to learn that a newer request has superseded it.