Fix bug in partial parsing of map literal.

dart/frog/leg/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);
 
   Token parseExpression(Token token) => skipExpression(token);
 
   Token skipExpression(Token token) {
     while (true) {
       final kind = token.kind;
       final value = token.stringValue;
       if ((kind === EOF_TOKEN) ||
           (value === ';') ||
           (value === ',') ||
           (value === ']'))
         return token;
-      if (value === '=' && token.next.stringValue === '{') {
-        // Handle cases like this:
-        // class Foo {
-        //   var map;
-        //   Foo() : map = {};
-        // }
-        BeginGroupToken begin = token.next;
-        token = (begin.endGroup !== null) ? begin.endGroup : token;
-        token = token.next;
-        continue;
+      if (value === '=') {
+        var nextValue = token.next.stringValue;
+        if (nextValue === 'const') {
+          token = token.next;
+          nextValue = token.next.stringValue;
+        }
+        if (nextValue === '{') {
+          // Handle cases like this:
+          // class Foo {
+          //   var map;
+          //   Foo() : map = {};
+          // }
+          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>{};
+          // }
+          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;
+        }
       }
       if (!mayParseFunctionExpressions && value === '{')
         return token;
       if ((value !== '<') && (token is BeginGroupToken)) {
         BeginGroupToken begin = token;
         token = (begin.endGroup !== null) ? begin.endGroup : token;
       }
       token = token.next;
     }
   }
@@ skipping 35 matching lines @@
         return token;
       }
       return listener.unexpected(token);
     }
     BeginGroupToken beginGroupToken = token;
     Token endToken = beginGroupToken.endGroup;
     listener.endFormalParameters(0, token, endToken);
     return endToken.next;
   }
 }