Fix parsing [a]sync[*] function body modifiers with Fasta.

pkg/front_end/lib/src/fasta/parser/listener.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.
 
 library fasta.parser.listener;
 
 import '../scanner/token.dart' show BeginGroupToken, Token;
 
 import '../util/link.dart' show Link;
 
@@ skipping 526 matching lines @@
   }
 
   void beginRedirectingFactoryBody(Token token) {}
 
   void endRedirectingFactoryBody(Token beginToken, Token endToken) {
     logEvent("RedirectingFactoryBody");
   }
 
   void beginReturnStatement(Token token) {}
 
+  void endExpressionFunctionBody(Token arrowToken, Token endToken) {
+    logEvent("ExpressionFunctionBody");
+  }
+
   void endReturnStatement(
       bool hasExpression, Token beginToken, Token endToken) {
     logEvent("ReturnStatement");
   }
 
   void beginSend(Token token) {}
 
   void endSend(Token token) {
     logEvent("Send");
   }
@@ skipping 406 matching lines @@
 
   final Map arguments;
 
   ParserError(this.beginOffset, this.endOffset, this.kind, this.arguments);
 
   ParserError.fromTokens(Token begin, Token end, ErrorKind kind, Map arguments)
       : this(begin.charOffset, end.charOffset + end.charCount, kind, arguments);
 
   String toString() => "@${beginOffset}: $kind $arguments";
 }