Maintain constant types of applications in TimeTravellingTreeCopier
Maintain constant types of applications in TimeTravellingTreeCopier

We keep the type (instead of retyping it) if

 - the function and argumens of an application are the same,
 - the application is a pure constant expression.

It's a shame to lose the type in this case. This does constrain what can
be done in transforms: It's forbidden to change a pure function with a constant
type so that the application no longer has that type.

dotty-staging/dotty,som-snytt/dotty,som-snytt/dotty,dotty-staging/dotty,lampepfl/dotty,lampepfl/dotty,dotty-staging/dotty,sjrd/dotty,som-snytt/dotty,sjrd/dotty,sjrd/dotty,dotty-staging/dotty,lampepfl/dotty,dotty-staging/dotty,lampepfl/dotty,som-snytt/dotty,sjrd/dotty,som-snytt/dotty,lampepfl/dotty,sjrd/dotty