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

src/ic/x87/ic-x87.cc

Index: src/ic/x87/ic-x87.cc
diff --git a/src/ic/x87/ic-x87.cc b/src/ic/x87/ic-x87.cc
index 396b85b116ab83c634f160cd9736b514704b6d3e..66e587383bc1cb0085388960869e8f8dfc8417ab 100644
--- a/src/ic/x87/ic-x87.cc
+++ b/src/ic/x87/ic-x87.cc
@@ -565,8 +565,8 @@ void KeyedStoreIC::GenerateMegamorphic(MacroAssembler* masm,
 
   Code::Flags flags =
       Code::RemoveHolderFromFlags(Code::ComputeHandlerFlags(Code::STORE_IC));
-  masm->isolate()->stub_cache()->GenerateProbe(masm, Code::STORE_IC, flags,
-                                               receiver, key, edi, no_reg);
+  masm->isolate()->stub_cache()->GenerateProbe(
+      masm, Code::KEYED_STORE_IC, flags, receiver, key, edi, no_reg);
 
   __ pop(VectorStoreICDescriptor::VectorRegister());
   __ pop(VectorStoreICDescriptor::SlotRegister());