fn uncapture_all(&mut self, unique_symbol: UniqueSymbol) {
        for scope in self.scopes.iter_mut() {
            scope.nonlocals.remove(&unique_symbol);
        }
    }
Removes a symbol as a captured variable in all
scopes. This ensures that the hoisting chain
only goes back to the most recent declaration.
passerine/src/compiler/hoist.rs