Make enum a keyword in dart2js.

pkg/compiler/lib/src/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.
 
 part of scanner;
 
 /**
  * A keyword in the Dart programming language.
  */
 class Keyword {
   static const List<Keyword> values = const <Keyword> [
       const Keyword("assert"),
       const Keyword("break"),
       const Keyword("case"),
       const Keyword("catch"),
       const Keyword("class"),
       const Keyword("const"),
       const Keyword("continue"),
       const Keyword("default"),
       const Keyword("do"),
       const Keyword("else"),
+      const Keyword("enum"),
       const Keyword("extends"),
       const Keyword("false"),
       const Keyword("final"),
       const Keyword("finally"),
       const Keyword("for"),
       const Keyword("if"),
       const Keyword("in"),
       const Keyword("new"),
       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("dynamic", isBuiltIn: true),
-      const Keyword("enum", 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),
@@ skipping 139 matching lines @@
 /**
  * A state that has no outgoing transitions.
  */
 class LeafKeywordState extends KeywordState {
   LeafKeywordState(String syntax) : super(Keyword.keywords[syntax]);
 
   KeywordState next(int c) => null;
 
   String toString() => keyword.syntax;
 }