don't run dart gen on JS patch code

test/dart_codegen/expect/core/iterable.dart

Index: test/dart_codegen/expect/core/iterable.dart
diff --git a/test/dart_codegen/expect/core/iterable.dart b/test/dart_codegen/expect/core/iterable.dart
index d81ca52c17dd4030176653afa5eb00da4f28aa43..8e8654cd9e7a7f0eb3e074575dacfd41f3b68024 100644
--- a/test/dart_codegen/expect/core/iterable.dart
+++ b/test/dart_codegen/expect/core/iterable.dart
@@ -78,8 +78,8 @@ class _GeneratorIterator<E> implements Iterator<E> {
       _index++;
       return true;
     } else {
-      _current = ((__x25) => DDC$RT.cast(__x25, Null, E, "CastLiteral",
-          """line 360, column 18 of dart:core/iterable.dart: """, __x25 is E,
+      _current = ((__x7) => DDC$RT.cast(__x7, Null, E, "CastLiteral",
+          """line 360, column 18 of dart:core/iterable.dart: """, __x7 is E,
           false))(null);
       return false;
     }