The new data structure, called `DecoratedClassHierarchy`, computes and
caches the variable substitutions necessary to relate a class to one
of its superclasses. In future CLs, we'll use this information to
create the appropriate contraints for override relationships, and to
compute the correct types when a method dispatch resolves to a method
declared in a superclass.
Note that the analyzer uses `InhertanceManager2` both to determine
what a method call resolves to and to record the appropriate
substitutions. We can take advantage of its determination of what a
method call resolves to (that information is stored in the resolved
AST), but we need to cmopute the substitutions separately because the
substitutions need to be decorated with nullability nodes.
Change-Id: Ifb334972e509b77151d41f7e0700cd590d7b5417
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/106800
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Dan Rubel <danrubel@google.com>
Paul Berry