History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on 42cd46c9b09e3eb804f933a8ff4ab4777ea35c17a8fd2a99eea4178d58264999. 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.