Expect a '(' before calling parseArguments (which asserts this is the case).

dart/frog/leg/scanner/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.
 
 /**
  * An event generating parser of Dart programs. This parser expects
  * all tokens in a linked list.
  */
 class Parser {
   final Listener listener;
@@ skipping 1207 matching lines @@
         (value === '[]') ||
         (value === '{')) {
       return parseLiteralListOrMap(constKeyword);
     }
     token = parseType(token);
     bool named = false;
     if (optional('.', token)) {
       named = true;
       token = parseIdentifier(token.next);
     }
+    expect('(', token);
     token = parseArguments(token);
     listener.handleConstExpression(constKeyword, named);
     return token;
   }
 
   Token parseLiteralInt(Token token) {
     listener.handleLiteralInt(token);
     return token.next;
   }
 
@@ skipping 413 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }