Implement hasConcreteMatch

pkg/compiler/lib/src/kernel/element_map_impl.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.kernel.element_map;
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers;
@@ skipping 1552 matching lines @@
         return member == element;
       }
       cls = elementEnvironment.getSuperClass(cls);
     }
     return false;
   }
 
   @override
   bool hasConcreteMatch(ClassEntity cls, Selector selector,
       {ClassEntity stopAtSuperclass}) {
-    throw new UnimplementedError('KernelClosedWorldMixin.hasConcreteMatch');
+    assert(
+        isInstantiated(cls), failedAt(cls, '$cls has not been instantiated.'));
+    MemberEntity element = elementEnvironment
+        .lookupClassMember(cls, selector.name, setter: selector.isSetter);
+    if (element == null) return false;
+
+    if (element.isAbstract) {
+      ClassEntity enclosingClass = element.enclosingClass;
+      return hasConcreteMatch(
+          elementEnvironment.getSuperClass(enclosingClass), selector);
+    }
+    return selector.appliesUntyped(element);
   }
 
   @override
   bool isNamedMixinApplication(ClassEntity cls) {
     throw new UnimplementedError(
         'KernelClosedWorldMixin.isNamedMixinApplication');
   }
 
   @override
   ClassEntity getAppliedMixin(ClassEntity cls) {
@@ skipping 532 matching lines @@
   ///
   /// These names are not used in generated code, just as element name.
   String _getClosureVariableName(String name, int id) {
     return "_captured_${name}_$id";
   }
 
   String getDeferredUri(ir.LibraryDependency node) {
     throw new UnimplementedError('JsKernelToElementMap.getDeferredUri');
   }
 }