Implement correct scope of for-in expression.

pkg/dart_parser/lib/src/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 dart_parser;
 
 import 'package:dart_scanner/src/keyword.dart' show
     Keyword;
 
 import 'package:dart_scanner/src/precedence.dart' show
@@ skipping 2754 matching lines @@
     listener.beginForStatementBody(token);
     token = parseStatement(token);
     listener.endForStatementBody(token);
     listener.endForStatement(expressionCount, forToken, token);
     return token;
   }
 
   Token parseForInRest(Token awaitToken, Token forToken, Token token) {
     assert(optional('in', token));
     Token inKeyword = token;
-    token = parseExpression(token.next);
+    token = token.next;
+    listener.beginForInExpression(token);
+    token = parseExpression(token);
+    listener.endForInExpression(token);
     token = expect(')', token);
     listener.beginForInBody(token);
     token = parseStatement(token);
     listener.endForInBody(token);
     listener.endForIn(awaitToken, forToken, inKeyword, token);
     return token;
   }
 
   Token parseWhileStatement(Token token) {
     Token whileToken = token;
@@ skipping 251 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }