pkg/docgen: fix type warnings

pkg/docgen/lib/src/models/model_helpers.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 docgen.model_helpers;
 
 import 'dart:collection';
 
 import '../exports/dart2js_mirrors.dart' as dart2js_mirrors;
 import '../exports/mirrors_util.dart' as dart2js_util;
@@ skipping 74 matching lines @@
     var docgenAnnotation = new Annotation(annotation, owningLibrary);
     if (!_SKIPPED_ANNOTATIONS.contains(dart2js_util.qualifiedNameOf(
         docgenAnnotation.mirror))) {
       annotations.add(docgenAnnotation);
     }
   });
   return annotations;
 }
 
 /// A declaration is private if itself is private, or the owner is private.
-// Issue(12202) - A declaration is public even if it's owner is private.

[kevmoo, 2014/04/22 22:12:58]

This was long-ago closed as by-design

 bool isHidden(DeclarationSourceMirror mirror) {
   if (mirror is LibraryMirror) {
     return _isLibraryPrivate(mirror);
   } else if (mirror.owner is LibraryMirror) {
     return (mirror.isPrivate || _isLibraryPrivate(mirror.owner) ||
         mirror.isNameSynthetic);
   } else {
     return (mirror.isPrivate || isHidden(mirror.owner) ||
         mirror.isNameSynthetic);
   }
@@ skipping 172 matching lines @@
   // the time.
   var sdkLibrary = LIBRARIES[dart2js_util.nameOf(mirror)];
   if (sdkLibrary != null) {
     return !sdkLibrary.documented;
   } else if (dart2js_util.nameOf(mirror).startsWith('_') || dart2js_util.nameOf(
       mirror).contains('._')) {
     return true;
   }
   return false;
 }