History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on 8dcaeeb848c691cd04f0f23e9e6d638be3b22bdbd124ed16312f28f825cbc3d4. 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.