Issue 26747. Report HintCode.UNDEFINED_SHOWN_NAME, but not HintCode.UNUSED_SHOWN_NAME for unresolve…

pkg/analyzer/lib/src/generated/resolver.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.src.generated.resolver;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 4637 matching lines @@
    */
   void _addShownNames(ImportDirective importDirective) {
     if (importDirective.combinators == null) {
       return;
     }
     List<SimpleIdentifier> identifiers = new List<SimpleIdentifier>();
     _unusedShownNamesMap[importDirective] = identifiers;
     for (Combinator combinator in importDirective.combinators) {
       if (combinator is ShowCombinator) {
         for (SimpleIdentifier name in combinator.shownNames) {
-          identifiers.add(name);
+          if (name.staticElement != null) {
+            identifiers.add(name);
+          }
         }
       }
     }
   }
 
   /**
    * Lookup and return the [Namespace] from the [_namespaceMap].
    *
    * If the map does not have the computed namespace, compute it and cache it in the map. If
    * [importDirective] is not resolved or is not resolvable, `null` is returned.
@@ skipping 6420 matching lines @@
       return null;
     }
     if (identical(node.staticElement, variable)) {
       if (node.inSetterContext()) {
         result = true;
       }
     }
     return null;
   }
 }