[runtime] Remove useless IN builtin.

src/compiler/js-generic-lowering.h

Index: src/compiler/js-generic-lowering.h
diff --git a/src/compiler/js-generic-lowering.h b/src/compiler/js-generic-lowering.h
index 1f997e4d69d053b2b8a628746bd99196508db916..ffce9126df74472808ef1d283f649e9370bfa172 100644
--- a/src/compiler/js-generic-lowering.h
+++ b/src/compiler/js-generic-lowering.h
@@ -38,7 +38,6 @@ class JSGenericLowering final : public Reducer {
   // Helpers to replace existing nodes with a generic call.
   void ReplaceWithCompareIC(Node* node, Token::Value token, Strength strength);
   void ReplaceWithStubCall(Node* node, Callable c, CallDescriptor::Flags flags);
-  void ReplaceWithBuiltinCall(Node* node, int context_index, int args);
   void ReplaceWithRuntimeCall(Node* node, Runtime::FunctionId f, int args = -1);
 
   Zone* zone() const;