History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on aa0bfbd11f02d9df4d579f4e8b0f0890d73629bc857878c414e882ebc42d3e85. 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.