History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on 107eaba52c9d9a3f7f363ef1801dac423bc0f01c0da8bfe608799b12038a0489. 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.