History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on ac689cd21adf10d5e791fe3251ff8a1e91fde2a093ab579cb467aa1ab9a2edc0. 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.