Fix for infinite resursion while finding a concrete method.

pkg/analyzer/test/generated/compile_time_error_code_test.dart

Index: pkg/analyzer/test/generated/compile_time_error_code_test.dart
diff --git a/pkg/analyzer/test/generated/compile_time_error_code_test.dart b/pkg/analyzer/test/generated/compile_time_error_code_test.dart
index d348b4bfc1b3ca5520ae1cf549cc9e61d8d9de70..34dd9b9745d9de998da40caa7779eae36799ea8d 100644
--- a/pkg/analyzer/test/generated/compile_time_error_code_test.dart
+++ b/pkg/analyzer/test/generated/compile_time_error_code_test.dart
@@ -5478,6 +5478,22 @@ class D implements A {}''');
     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);