[turbofan] Remove dead ChangeToUndefined in intrinsic lowering.

src/compiler/js-intrinsic-lowering.h

Index: src/compiler/js-intrinsic-lowering.h
diff --git a/src/compiler/js-intrinsic-lowering.h b/src/compiler/js-intrinsic-lowering.h
index a43ed01166997428f89cf4547c0c98951f50b9e5..eebabf4460669ea8682a382f119f703ba907e340 100644
--- a/src/compiler/js-intrinsic-lowering.h
+++ b/src/compiler/js-intrinsic-lowering.h
@@ -70,7 +70,6 @@ class JSIntrinsicLowering final : public AdvancedReducer {
   Reduction Change(Node* node, const Operator* op, Node* a, Node* b, Node* c);
   Reduction Change(Node* node, const Operator* op, Node* a, Node* b, Node* c,
                    Node* d);
-  Reduction ChangeToUndefined(Node* node, Node* effect = nullptr);
   Reduction Change(Node* node, Callable const& callable,
                    int stack_parameter_count);