Revert "Support unary - operator."

dart/lib/compiler/implementation/scanner/token.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.
 
 const int EOF_TOKEN = 0;
 
 const int KEYWORD_TOKEN = $k;
 const int IDENTIFIER_TOKEN = $a;
 const int DOUBLE_TOKEN = $d;
 const int INT_TOKEN = $i;
@@ skipping 238 matching lines @@
 class BeginGroupToken extends StringToken {
   Token endGroup;
   BeginGroupToken(PrecedenceInfo info, String value, int charOffset)
     : super(info, value, charOffset);
 }
 
 bool isUserDefinableOperator(String value) {
   return
     (value === '==') ||
     (value === '~') ||
+    (value === 'negate') ||
     (value === '[]') ||
     (value === '[]=') ||
     (value === '*') ||
     (value === '/') ||
     (value === '%') ||
     (value === '~/') ||
     (value === '+') ||
     (value === '-') ||
     (value === '<<') ||
     (value === '>>>') ||
@@ skipping 225 matching lines @@
 
 const PrecedenceInfo HEXADECIMAL_INFO =
   const PrecedenceInfo(const SourceString('hexadecimal'), 0, HEXADECIMAL_TOKEN);
 
 const PrecedenceInfo COMMENT_INFO =
   const PrecedenceInfo(const SourceString('comment'), 0, COMMENT_TOKEN);
 
 // For reporting lexical errors.
 const PrecedenceInfo ERROR_INFO =
   const PrecedenceInfo(const SourceString('?'), 0, UNKNOWN_TOKEN);