Use a dictionary-mode code cache on the map rather than a dual system.

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index 1e12789ce602b6989a3f3354f4c21a0488a2d148..9cb6ebb8e922d6b8bf7d985ec6412180dcdadfad 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -3749,8 +3749,8 @@ void LoadICStub::GenerateImpl(MacroAssembler* masm, bool in_frame) {
   __ bind(&not_array);
   __ CompareRoot(feedback, Heap::kmegamorphic_symbolRootIndex);
   __ j(not_equal, &miss);
-  Code::Flags code_flags = Code::RemoveTypeAndHolderFromFlags(
-      Code::ComputeHandlerFlags(Code::LOAD_IC));
+  Code::Flags code_flags =
+      Code::RemoveHolderFromFlags(Code::ComputeHandlerFlags(Code::LOAD_IC));
   masm->isolate()->stub_cache()->GenerateProbe(
       masm, Code::LOAD_IC, code_flags, receiver, name, feedback, no_reg);
 
@@ -3891,8 +3891,8 @@ void VectorStoreICStub::GenerateImpl(MacroAssembler* masm, bool in_frame) {
   __ CompareRoot(feedback, Heap::kmegamorphic_symbolRootIndex);
   __ j(not_equal, &miss);
 
-  Code::Flags code_flags = Code::RemoveTypeAndHolderFromFlags(
-      Code::ComputeHandlerFlags(Code::STORE_IC));
+  Code::Flags code_flags =
+      Code::RemoveHolderFromFlags(Code::ComputeHandlerFlags(Code::STORE_IC));
   masm->isolate()->stub_cache()->GenerateProbe(masm, Code::STORE_IC, code_flags,
                                                receiver, key, feedback, no_reg);