Mark FunctionExpression elements as used in DeclarationResolver.

pkg/analyzer/test/generated/declaration_resolver_test.dart

 // Copyright (c) 2015, 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 engine.declaration_resolver_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/ast/utilities.dart';
@@ skipping 284 matching lines @@
 ''';
     CompilationUnit unit = resolveSource(code);
     FunctionElement setterElement =
         _findSimpleIdentifier(unit, code, 'zzz(x)').staticElement;
     // re-resolve
     CompilationUnit unit2 = _cloneResolveUnit(unit);
     SimpleIdentifier setterName = _findSimpleIdentifier(unit2, code, 'zzz(x)');
     expect(setterName.staticElement, same(setterElement));
   }
 
+  void test_visitFunctionExpression() {
+    String code = r'''
+main(List<String> items) {
+  items.forEach((item) {});
+}
+''';
+    CompilationUnit unit = resolveSource(code);
+    // re-resolve
+    _cloneResolveUnit(unit);
+    // no other validations than built into DeclarationResolver
+  }
+
   void test_visitMethodDeclaration_getter_duplicate() {
     String code = r'''
 class C {
   int get zzz => 1;
   String get zzz => null;
 }
 ''';
     CompilationUnit unit = resolveSource(code);
     PropertyAccessorElement firstElement =
         _findSimpleIdentifier(unit, code, 'zzz => 1').staticElement;
@@ skipping 120 matching lines @@
     expect(element.type.toString(), "<T>(T, T) → T");
     expect(t.element, same(tElement));
 
     // re-resolve
     CompilationUnit unit2 = _cloneResolveUnit(unit);
     node = _findSimpleIdentifier(unit2, code, 'max').parent;
     t = node.typeParameters.typeParameters[0];
     expect(t.element, same(tElement));
   }
 }