don't run dart gen on JS patch code

test/dart_codegen/expect/core/function.dart

Index: test/dart_codegen/expect/core/function.dart
diff --git a/test/dart_codegen/expect/core/function.dart b/test/dart_codegen/expect/core/function.dart
index 50ae943c379c9134dcf7fb52295f73746018d9f3..be250b164678ae3cb5637c8e6d8521bb727bef91 100644
--- a/test/dart_codegen/expect/core/function.dart
+++ b/test/dart_codegen/expect/core/function.dart
@@ -1,11 +1,8 @@
 part of dart.core;
 
 abstract class Function {
-  static apply(Function function, List positionalArguments,
-      [Map<Symbol, dynamic> namedArguments]) {
-    return Primitives.applyFunction(function, positionalArguments,
-        namedArguments == null ? null : _toMangledNames(namedArguments));
-  }
+  external static apply(Function function, List positionalArguments,
+      [Map<Symbol, dynamic> namedArguments]);
   int get hashCode;
   bool operator ==(Object other);
 }