[element model] migrate least_greatest_closure

Change-Id: Ide8b5cb1659785d6b84e373ee798dde43e8a136b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403624
Commit-Queue: Phil Quitslund <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>

Author: pq

pkg/analyzer/analyzer_use_new_elements.txt

@@ -31,7 +31,6 @@ lib/src/dart/element/field_name_non_promotability_info.dart
 lib/src/dart/element/generic_inferrer.dart
 lib/src/dart/element/greatest_lower_bound.dart
 lib/src/dart/element/inheritance_manager3.dart
-lib/src/dart/element/least_greatest_closure.dart
 lib/src/dart/element/least_upper_bound.dart
 lib/src/dart/element/member.dart
 lib/src/dart/element/name_union.dart

pkg/analyzer/lib/src/dart/element/least_greatest_closure.dart

@@ -70,7 +70,7 @@ class LeastGreatestClosureHelper extends ReplacementVisitor {
     //   and `L` contains any free type variables from any of the `Bi`:
     //  - The least closure of `S` with respect to `L` is `Never`
     //  - The greatest closure of `S` with respect to `L` is `Function`
-    for (var typeParameter in node.typeFormals) {
+    for (var typeParameter in node.typeParameters) {
       if (typeParameter.bound case TypeImpl bound?
           when bound.referencesAny2(eliminationTargets)) {
         return _functionReplacement;