Add support for parsing #void with Fasta.

pkg/front_end/lib/src/fasta/parser/parser.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.parser;
 
 import '../scanner.dart' show ErrorToken;
 
 import '../scanner/recover.dart' show closeBraceFor, skipToEof;
 
@@ skipping 2937 matching lines @@
   }
 
   Token parseLiteralSymbol(Token token) {
     Token hashToken = token;
     listener.beginLiteralSymbol(hashToken);
     token = token.next;
     if (isUserDefinableOperator(token.stringValue)) {
       listener.handleOperator(token);
       listener.endLiteralSymbol(hashToken, 1);
       return token.next;
+    } else if (identical(token.stringValue, 'void')) {
+      listener.handleSymbolVoid(token);
+      listener.endLiteralSymbol(hashToken, 1);
+      return token.next;
     } else {
       int count = 1;
       token = parseIdentifier(token, IdentifierContext.literalSymbol);
       while (identical(token.stringValue, '.')) {
         count++;
         token = parseIdentifier(
             token.next, IdentifierContext.literalSymbolContinuation);
       }
       listener.endLiteralSymbol(hashToken, count);
       return token;
@@ skipping 591 matching lines @@
         break;
     }
     if (isRecoverable) {
       listener.handleRecoverableError(token, kind, arguments);
       return null;
     } else {
       return listener.handleUnrecoverableError(token, kind, arguments);
     }
   }
 }