Require two type arguments for map literals (issue 4522).

pkg/dartdoc/comment_map.dart

 // Copyright (c) 2012, 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.
 
 /**
  * The cached lookup-table to associate doc comments with spans. The outer map
  * is from filenames to doc comments in that file. The inner map maps from the
  * token positions to doc comments. Each position is the starting offset of the
  * next non-comment token *following* the doc comment. For example, the position
  * for this comment would be the position of the "class" token below.
  */
 class CommentMap {
   /**
    * Maps from (filename, pos) to doc comment preceding the token at that
    * position.
    */
   Map<String, Map<int, String>> _comments;
 
   /** Doc comments before #library() directives. */
   Map<String, String> _libraryComments;
 
   CommentMap()
-    : _comments = <Map<int, String>>{},
-      _libraryComments = <String>{};
+    : _comments = <String, Map<int, String>>{},
+      _libraryComments = <String, String>{};
 
   /** Finds the doc comment preceding the given source span, if there is one. */
   String find(Location span) {
     if (span == null) return null;
 
     _ensureFileParsed(span.source);
     final comment = _comments[span.source.uri.toString()][span.start];
     if (comment == null) return '';
     return comment;
   }
@@ skipping 74 matching lines @@
         line = line.substring(1);
       }
 
       buf.add(line);
       buf.add('\n');
     }
 
     return buf.toString();
   }
 }