History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on 4c77a1c8aad8799227421360bab76001757ca9fe11cf66324a7d1e6997ef6b7b. 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.