Support `void` as generic argument.

pkg/front_end/lib/src/fasta/scanner/keyword.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.
 
 library fasta.scanner.keywords;
 
 import 'characters.dart' show $a, $z, $A, $Z;
 
 import 'precedence.dart' show PrecedenceInfo;
 
@@ skipping 26 matching lines @@
     const Keyword("null"),
     const Keyword("rethrow"),
     const Keyword("return"),
     const Keyword("super"),
     const Keyword("switch"),
     const Keyword("this"),
     const Keyword("throw"),
     const Keyword("true"),
     const Keyword("try"),
     const Keyword("var"),
-    const Keyword("void"),
     const Keyword("while"),
     const Keyword("with"),
 
     // TODO(ahe): Don't think this is a reserved word.
     // See: http://dartbug.com/5579
     const Keyword("is", info: IS_INFO),
 
     const Keyword("abstract", isBuiltIn: true),
     const Keyword("as", info: AS_INFO, isBuiltIn: true),
     const Keyword("covariant", isBuiltIn: true),
     const Keyword("dynamic", isBuiltIn: true),
     const Keyword("export", isBuiltIn: true),
     const Keyword("external", isBuiltIn: true),
     const Keyword("factory", isBuiltIn: true),
     const Keyword("get", isBuiltIn: true),
     const Keyword("implements", isBuiltIn: true),
     const Keyword("import", isBuiltIn: true),
     const Keyword("library", isBuiltIn: true),
     const Keyword("operator", isBuiltIn: true),
     const Keyword("part", isBuiltIn: true),
     const Keyword("set", isBuiltIn: true),
     const Keyword("static", isBuiltIn: true),
     const Keyword("typedef", isBuiltIn: true),
+    const Keyword("void", isBuiltIn: true),
 
     const Keyword("async", isPseudo: true),
     const Keyword("await", isPseudo: true),
     const Keyword("deferred", isPseudo: true),
     const Keyword("Function", isPseudo: true),
     const Keyword("hide", isPseudo: true),
     const Keyword("native", isPseudo: true),
     const Keyword("of", isPseudo: true),
     const Keyword("on", isPseudo: true),
     const Keyword("patch", isPseudo: true),
@@ skipping 161 matching lines @@
 class LeafKeywordState implements KeywordState {
   final Keyword keyword;
 
   LeafKeywordState(String syntax) : keyword = Keyword.keywords[syntax];
 
   KeywordState next(int c) => null;
   KeywordState nextCapital(int c) => null;
 
   String toString() => keyword.syntax;
 }