Fix for infinite resursion while finding a concrete method.

pkg/analyzer/test/generated/compile_time_error_code_test.dart

 // Copyright (c) 2014, 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 analyzer.test.generated.compile_time_error_code_test;
 
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/parser.dart' show ParserErrorCode;
 import 'package:analyzer/src/generated/source_io.dart';
@@ skipping 5460 matching lines @@
 
   void test_recursiveInterfaceInheritanceBaseCaseExtends() {
     Source source = addSource("class A extends A {}");
     computeLibrarySourceErrors(source);
     assertErrors(source, [
       CompileTimeErrorCode.RECURSIVE_INTERFACE_INHERITANCE_BASE_CASE_EXTENDS
     ]);
     verify([source]);
   }
 
+  void test_recursiveInterfaceInheritanceBaseCaseExtends_abstract() {
+    Source source = addSource(r'''
+class C extends C {
+  var bar = 0;
+  m();
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [
+      CompileTimeErrorCode.RECURSIVE_INTERFACE_INHERITANCE_BASE_CASE_EXTENDS,
+      StaticWarningCode.CONCRETE_CLASS_WITH_ABSTRACT_MEMBER,
+      StaticWarningCode.NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER_ONE
+    ]);
+    verify([source]);
+  }
+
   void test_recursiveInterfaceInheritanceBaseCaseImplements() {
     Source source = addSource("class A implements A {}");
     computeLibrarySourceErrors(source);
     assertErrors(source, [
       CompileTimeErrorCode.RECURSIVE_INTERFACE_INHERITANCE_BASE_CASE_IMPLEMENTS
     ]);
     verify([source]);
   }
 
   void test_recursiveInterfaceInheritanceBaseCaseImplements_typeAlias() {
@@ skipping 830 matching lines @@
         source, [CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR]);
     verify([source]);
     reset();
   }
 
   void _check_wrongNumberOfParametersForOperator1(String name) {
     _check_wrongNumberOfParametersForOperator(name, "");
     _check_wrongNumberOfParametersForOperator(name, "a, b");
   }
 }