pkg/docgen: using consistently ordered maps for caching

pkg/docgen/lib/src/models/indexable.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.models.indexable;
 
+import 'dart:collection';
+
 import 'package:markdown/markdown.dart' as markdown;
 
 import '../exports/mirrors_util.dart' as dart2js_util;
 import '../exports/source_mirrors.dart';
 
 import '../library_helpers.dart';
 import 'library.dart';
 import 'mirror_based.dart';
 import 'model_helpers.dart';
 
@@ skipping 26 matching lines @@
   /// methods need to resolve links differently from the superclass.
   String unresolvedComment = '';
 
   Indexable(TMirror mirror)
       : this.mirror = mirror,
         this.isPrivate = isHidden(mirror) {
 
     var mirrorQualifiedName = dart2js_util.qualifiedNameOf(this.mirror);
 
     var map = _mirrorToDocgen.putIfAbsent(mirrorQualifiedName,
-        () => new Map<String, Indexable>());
+        () => new HashMap<String, Indexable>());
 
     var added = false;
     map.putIfAbsent(owner.docName, () {
       added = true;
       return this;
     });
 
     if (!added) {
       throw new StateError('An indexable has already been stored for '
           '${owner.docName}');
@@ skipping 133 matching lines @@
   bool isValidMirror(DeclarationMirror mirror);
 }
 
 /// Index of all the dart2js mirrors examined to corresponding MirrorBased
 /// docgen objects.
 ///
 /// Used for lookup because of the dart2js mirrors exports
 /// issue. The second level map is indexed by owner docName for faster lookup.
 /// Why two levels of lookup? Speed, man. Speed.
 final Map<String, Map<String, Indexable>> _mirrorToDocgen =
-    new Map<String, Map<String, Indexable>>();
+    new HashMap<String, Map<String, Indexable>>();
 
 Iterable<Indexable> get allIndexables =>
     _mirrorToDocgen.values.expand((map) => map.values);
 
 Map<String, Indexable> lookupIndexableMap(DeclarationMirror mirror) {
   return _mirrorToDocgen[dart2js_util.qualifiedNameOf(mirror)];
 }