History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on 69e4f27c5633a370168dbece49d20d20d7518d2c4c0e4d1ca3d51ef0e67b3cd1. 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.