Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
When one spells a compound declaration name in the source (e.g.,
insertSubview(_:aboveSubview:), keep track of the locations of the
base name, parentheses, and argument labels.
