[turbofan] Inline calls to CPP builtins

src/builtins/x64/builtins-x64.cc

Index: src/builtins/x64/builtins-x64.cc
diff --git a/src/builtins/x64/builtins-x64.cc b/src/builtins/x64/builtins-x64.cc
index 944c7845276155544df0b2e5d83521bc0acb5fc4..ed370a30174da95901eb377246cfdbf1d738371d 100644
--- a/src/builtins/x64/builtins-x64.cc
+++ b/src/builtins/x64/builtins-x64.cc
@@ -28,6 +28,9 @@ void Builtins::Generate_Adaptor(MacroAssembler* masm, Address address,
   // -----------------------------------
   __ AssertFunction(rdi);
 
+  // The logic contained here is mirrored for TurboFan inlining in
+  // JSTypedLowering::ReduceJSCall{Function,Construct}. Keep these in sync.
+
   // Make sure we operate in the context of the called function (for example
   // ConstructStubs implemented in C++ will be run in the context of the caller
   // instead of the callee, due to the way that [[Construct]] is defined for