[turbofan] First steps towards optimizing for-in loops.

src/compiler/js-generic-lowering.cc

Index: src/compiler/js-generic-lowering.cc
diff --git a/src/compiler/js-generic-lowering.cc b/src/compiler/js-generic-lowering.cc
index a97a00062cb222e7b34021942b497b3b838bbe64..876a4563591cf7999a8aead27b3610d31123a8be 100644
--- a/src/compiler/js-generic-lowering.cc
+++ b/src/compiler/js-generic-lowering.cc
@@ -606,8 +606,7 @@ void JSGenericLowering::LowerJSForInPrepare(Node* node) {
   Node* cache_type = effect = graph()->NewNode(
       common()->Call(descriptor),
       jsgraph()->CEntryStubConstant(function->result_size), object,
-      jsgraph()->ExternalConstant(
-          ExternalReference(function->function_id, isolate())),
+      jsgraph()->ExternalConstant(function->function_id),
       jsgraph()->Int32Constant(1), context, frame_state, effect, control);
   control = graph()->NewNode(common()->IfSuccess(), cache_type);