History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on a268d4df52bf2e3806d9caaec2d5bc3b8f1128968636a1e84513588fb656b7ee. 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.