We already had this functionality in the FixitApplyDiagnosticConsumer,
but we also need it in the AST passes because different entries in the
API diff data may drive identical fix-its, namely a general type rename,
which can occur anywhere a DeclRef appears, but also for function overrides'
parameter type changes, which are context specific.
rdar://problem/32431533
This handles optionality changes and type rewrites in function param and return types and constructor param and failability types.
Resolves rdar://problem/31766010
This adds an adapter class that wraps Clang's lib/Edit
Commit and EditedSource classes for use in the initial
"syntactic" passes. Once the passes have completed,
the resulting source file is then passed to the Swift compiler
fix-it passes.
rdar://problem/30926261
