This adds helpers for creating variables corresponding to the new variable model. This prepares for removing the LegacyVariable and only createing the variables.
This includes a fix for using the new LocalVariable for FunctionDeclaration.
Change-Id: Ib82e12ceb11cf6aa80185bdfeb559461c641dc15
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/506241
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Johnni Winther
06e0f58562