History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on 09ffa7b600a913f425e49a1c43cc9ca255b7cbf28d256bd91c16d1aa76392a14. Every change that wrote or deleted one of these lines, or deleted a line from between them. Exact, because each line keeps its identity across edits; edits elsewhere in the file are not here. Also: oxy log -L 107,134:crates/backdrop/src/lib.rs.