Add support for metadata on type variables to Fasta parser.

pkg/analyzer/test/generated/parser_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.parser_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
@@ skipping 14712 matching lines @@
     expect(functionType.parameters, isNotNull);
     expect(functionType.returnType, isNotNull);
     expect(functionType.typeParameters, isNull);
   }
 
   void test_parseTypeAlias_genericFunction_withDocComment() {
     createParser('/// Doc\ntypedef F = bool Function();');
     var typeAlias = parseFullCompilationUnitMember() as GenericTypeAlias;
     expectCommentText(typeAlias.documentationComment, '/// Doc');
   }
+
+  void test_parseTypeVariable_withDocumentationComment() {
+    createParser('''
+class A<
+    /// Doc
+    B> {}
+''');
+    var classDeclaration = parseFullCompilationUnitMember() as ClassDeclaration;
+    var typeVariable = classDeclaration.typeParameters.typeParameters[0];
+    expectCommentText(typeVariable.documentationComment, '/// Doc');
+  }
 }