Implement correct scope of for-in expression.

pkg/dart_parser/lib/src/parser.dart

Index: pkg/dart_parser/lib/src/parser.dart
diff --git a/pkg/dart_parser/lib/src/parser.dart b/pkg/dart_parser/lib/src/parser.dart
index 783abc0ca48dd5c35cbb355fd5e018b8566e6382..a886e1493a13511c4f1f3b0d3309c038af3caa92 100644
--- a/pkg/dart_parser/lib/src/parser.dart
+++ b/pkg/dart_parser/lib/src/parser.dart
@@ -2772,7 +2772,10 @@ class Parser {
   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);