don't run dart gen on JS patch code

test/dart_codegen/expect/core/int.dart

Index: test/dart_codegen/expect/core/int.dart
diff --git a/test/dart_codegen/expect/core/int.dart b/test/dart_codegen/expect/core/int.dart
index f044dc86e71aa6624dd6b537d37fdf9784d0dbc5..f6b6e87263300426dbdda4b0c01a3a86932b3abe 100644
--- a/test/dart_codegen/expect/core/int.dart
+++ b/test/dart_codegen/expect/core/int.dart
@@ -1,10 +1,7 @@
 part of dart.core;
 
 abstract class int extends num {
-  factory int.fromEnvironment(String name, {int defaultValue}) {
-    throw new UnsupportedError(
-        'int.fromEnvironment can only be used as a const constructor');
-  }
+  external const factory int.fromEnvironment(String name, {int defaultValue});
   int operator &(int other);
   int operator |(int other);
   int operator ^(int other);
@@ -29,9 +26,6 @@ abstract class int extends num {
   double truncateToDouble();
   String toString();
   String toRadixString(int radix);
-  static int parse(String source, {int radix, int onError(String source)}) {
-    return ((__x24) => DDC$RT.cast(__x24, dynamic, int, "CastGeneral",
-        """line 281, column 12 of dart:core/int.dart: """, __x24 is int,
-        true))(Primitives.parseInt(source, radix, onError));
-  }
+  external static int parse(String source,
+      {int radix, int onError(String source)});
 }