Store return type and parameters separately in GenericFunctionTypeElementForLink.
Store return type and parameters separately in GenericFunctionTypeElementForLink.

This will allow us to create a synthetic
GenericFunctionTypeElementForLink representing the function type
defined by an old-style typedef.  That in turn will be necessary to
fix some incompatibilities between the summary linker and element
model representations of typedefs.

Change-Id: Ia3622d58cac25976022bf79a0ac47b190f1f411c
Reviewed-on: https://dart-review.googlesource.com/c/78920
Commit-Queue: Paul Berry <72d414e3a99fb120308437779d51667bcc0984eb@google.com>
Commit-Queue: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Auto-Submit: Paul Berry <72d414e3a99fb120308437779d51667bcc0984eb@google.com>
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>

dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk