Support unary - operator.

dart/lib/compiler/implementation/scanner/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.
 
 /**
  * An event generating parser of Dart programs. This parser expects
  * all tokens in a linked list (aka a token stream).
  *
  * The class [Scanner] is used to generate a token stream. See the
  * file scanner.dart.
@@ skipping 707 matching lines @@
       token = parseIdentifier(token.next);
     }
     token = parseFormalParameters(token);
     token = parseFunctionBody(token, false);
     listener.endFactoryMethod(start, period, token);
     return token.next;
   }
 
   Token parseOperatorName(Token token) {
     assert(optional('operator', token));
-    if (isUserDefinableOperator(token.next.stringValue)) {
+    if (isUserDefinableOperator(token.next.stringValue)
+        // TODO(ahe): Remove negate.
+        || token.next.value == const SourceString("negate")) {
       Token operator = token;
       token = token.next;
       listener.handleOperatorName(operator, token);
       return token.next;
     } else {
       return parseIdentifier(token);
     }
   }
 
   Token parseFunction(Token token, Token getOrSet) {
@@ skipping 1099 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }