Don't use the keyed slow stub for named handlers.

src/ic/x64/ic-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/codegen.h"
 #include "src/ic/ic.h"
 #include "src/ic/ic-compiler.h"
 #include "src/ic/stub-cache.h"
@@ skipping 551 matching lines @@
   // change the IC from any downstream misses, a dummy vector can be used.
   Handle<TypeFeedbackVector> dummy_vector =
       TypeFeedbackVector::DummyVector(masm->isolate());
   int slot_index = dummy_vector->GetIndex(
       FeedbackVectorSlot(TypeFeedbackVector::kDummyKeyedStoreICSlot));
   __ Move(vector, dummy_vector);
   __ Move(slot, Smi::FromInt(slot_index));
 
   Code::Flags flags =
       Code::RemoveHolderFromFlags(Code::ComputeHandlerFlags(Code::STORE_IC));
-  masm->isolate()->stub_cache()->GenerateProbe(masm, Code::STORE_IC, flags,
-                                               receiver, key, r9, no_reg);
+  masm->isolate()->stub_cache()->GenerateProbe(
+      masm, Code::KEYED_STORE_IC, flags, receiver, key, r9, no_reg);
   // Cache miss.
   __ jmp(&miss);
 
   // Extra capacity case: Check if there is extra capacity to
   // perform the store and update the length. Used for adding one
   // element to the array by writing to array[array.length].
   __ bind(&extra);
   // receiver is a JSArray.
   // rbx: receiver's elements array (a FixedArray)
   // flags: smicompare (receiver.length(), rbx)
@@ skipping 261 matching lines @@
   Condition cc =
       (check == ENABLE_INLINED_SMI_CHECK)
           ? (*jmp_address == Assembler::kJncShortOpcode ? not_zero : zero)
           : (*jmp_address == Assembler::kJnzShortOpcode ? not_carry : carry);
   *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64