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

lib/compiler/implementation/scanner/partial_parser.dart

 // Copyright (c) 2011, 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.
 
 class PartialParser extends Parser {
   PartialParser(Listener listener) : super(listener);
 
   Token parseClassBody(Token token) => skipClassBody(token);
 
   Token fullParseClassBody(Token token) => super.parseClassBody(token);
@@ skipping 23 matching lines @@
           // }
           BeginGroupToken begin = token.next;
           token = (begin.endGroup !== null) ? begin.endGroup : token;
           token = token.next;
           continue;
         }
         if (nextValue === '<') {
           // Handle cases like this:
           // class Foo {
           //   var map;
-          //   Foo() : map = <Foo>{};
+          //   Foo() : map = <String, Foo>{};
           // }
           BeginGroupToken begin = token.next;
           token = (begin.endGroup !== null) ? begin.endGroup : token;
           token = token.next;
           if (token.stringValue === '{') {
             begin = token;
             token = (begin.endGroup !== null) ? begin.endGroup : token;
             token = token.next;
           }
           continue;
@@ skipping 45 matching lines @@
         return token;
       }
       return listener.unexpected(token);
     }
     BeginGroupToken beginGroupToken = token;
     Token endToken = beginGroupToken.endGroup;
     listener.endFormalParameters(0, token, endToken);
     return endToken.next;
   }
 }