fix #25578, implement @covariant parameter overrides

pkg/analyzer/lib/src/summary/link.dart

Index: pkg/analyzer/lib/src/summary/link.dart
diff --git a/pkg/analyzer/lib/src/summary/link.dart b/pkg/analyzer/lib/src/summary/link.dart
index 7d77fb860dffa5d2b86c209e0aea550d9220a8e7..868218a80f503cd947d0aaf4cd018662bf0189ac 100644
--- a/pkg/analyzer/lib/src/summary/link.dart
+++ b/pkg/analyzer/lib/src/summary/link.dart
@@ -3901,6 +3901,9 @@ class ParameterElementForLink implements ParameterElementImpl {
   DartType _inferredType;
   DartType _declaredType;
 
+  @override
+  bool inheritsCovariant = false;
+
   ParameterElementForLink(this.enclosingElement, this._unlinkedParam,
       this._typeParameterContext, this.compilationUnit, this._parameterIndex) {
     if (_unlinkedParam.initializer?.bodyExpr != null) {
@@ -3916,6 +3919,9 @@ class ParameterElementForLink implements ParameterElementImpl {
       !_unlinkedParam.isFunctionTyped && _unlinkedParam.type == null;
 
   @override
+  bool get isCovariant => false;
+
+  @override
   String get name => _unlinkedParam.name;
 
   @override