Implement hasConcreteMatch

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

Index: pkg/compiler/lib/src/kernel/element_map_impl.dart
diff --git a/pkg/compiler/lib/src/kernel/element_map_impl.dart b/pkg/compiler/lib/src/kernel/element_map_impl.dart
index da6e337738f1c799d51464858231d81e5f361d50..14b9fcde992e61ee05423c504eb9e9779c5ab9db 100644
--- a/pkg/compiler/lib/src/kernel/element_map_impl.dart
+++ b/pkg/compiler/lib/src/kernel/element_map_impl.dart
@@ -1570,7 +1570,18 @@ abstract class KernelClosedWorldMixin implements ClosedWorldBase {
   @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