fix return type comment parsing for top-level generic function

pkg/analyzer/test/generated/resolver_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 engine.resolver_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/context/context.dart' as newContext;
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 12160 matching lines @@
     VariableDeclaration declaration =
         identifier.getAncestor((node) => node is VariableDeclaration);
     expect(declaration.initializer.staticType.name, 'String');
     expect(declaration.initializer.propagatedType, isNull);
   }
 
   void test_genericFunction() {
     if (!AnalysisEngine.instance.useTaskModel) {
       return;
     }
-    // TODO(jmesserly): we're missing a case in the parser for the return type,
-    // so "dynamic" must be used to workaround this.
-    _resolveTestUnit(r'''
-dynamic/*=T*/ f/*<T>*/(/*=T*/ x) => null;
-''');
+    _resolveTestUnit(r'/*=T*/ f/*<T>*/(/*=T*/ x) => null;');
     SimpleIdentifier f = _findIdentifier('f');
     FunctionElementImpl e = f.staticElement;
     expect(e.typeParameters.toString(), '[T]');
     expect(e.type.typeParameters.toString(), '[T]');
     expect(e.type.typeParameters[0].type, e.type.typeArguments[0]);
     expect(e.type.toString(), '(T) → T');
 
     // Substitute for T
     DartType t = e.typeParameters[0].type;
     FunctionType ft = e.type.substitute2([typeProvider.stringType], [t]);
@@ skipping 3016 matching lines @@
 
   void _resolveTestUnit(String code) {
     testCode = code;
     testSource = addSource(testCode);
     LibraryElement library = resolve2(testSource);
     assertNoErrors(testSource);
     verify([testSource]);
     testUnit = resolveCompilationUnit(testSource, library);
   }
 }