History of Engine::tick 2 changes

In crates/backdrop/src/lib.rs, lines 107–134 on 951aed50c2f5854e52d81f28953e61194b4f20492918fe9bbb1ed6c8fd1e64cc. 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.