Elements. Migrate FunctionReferenceResolver.

Change-Id: I4a9c0bafa016054a2cfeb1b9dcdfd191261bc456
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/406402
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>

Author: scheglov

pkg/analyzer/lib/src/dart/ast/ast.dart

@@ -9725,11 +9725,11 @@ final class ImplicitCallReferenceImpl extends ExpressionImpl
   List<DartType> typeArgumentTypes;
 
   @override
-  MethodElement staticElement;
+  MethodElement2 element;
 
   ImplicitCallReferenceImpl({
     required ExpressionImpl expression,
-    required this.staticElement,
+    required this.element,
     required TypeArgumentListImpl? typeArguments,
     required this.typeArgumentTypes,
   })  : _expression = expression,
@@ -9741,10 +9741,6 @@ final class ImplicitCallReferenceImpl extends ExpressionImpl
   @override
   Token get beginToken => expression.beginToken;
 
-  @experimental
-  @override
-  MethodElement2? get element => (staticElement as MethodFragment?)?.element;
-
   @override
   Token get endToken => typeArguments?.endToken ?? expression.endToken;
 
@@ -9759,6 +9755,10 @@ final class ImplicitCallReferenceImpl extends ExpressionImpl
   Precedence get precedence =>
       typeArguments == null ? expression.precedence : Precedence.postfix;
 
+  @experimental
+  @override
+  MethodElement get staticElement => element.asElement;
+
   @override
   TypeArgumentListImpl? get typeArguments => _typeArguments;