Don't double smi-tag the mask used to check read-only / field mode in the dictionary-store-stub on …

src/ic/x64/ic-x64.cc

Index: src/ic/x64/ic-x64.cc
diff --git a/src/ic/x64/ic-x64.cc b/src/ic/x64/ic-x64.cc
index f125322645ceaf6a565f80187a6a86d51ea926c7..c7345603b7459c06602b4d23e47635629effb6ce 100644
--- a/src/ic/x64/ic-x64.cc
+++ b/src/ic/x64/ic-x64.cc
@@ -119,9 +119,8 @@ static void GenerateDictionaryStore(MacroAssembler* masm, Label* miss_label,
       NameDictionary::kElementsStartIndex * kPointerSize;
   const int kDetailsOffset = kElementsStartOffset + 2 * kPointerSize;
   const int kTypeAndReadOnlyMask =
-      (PropertyDetails::TypeField::kMask |
-       PropertyDetails::AttributesField::encode(READ_ONLY))
-      << kSmiTagSize;
+      PropertyDetails::TypeField::kMask |
+      PropertyDetails::AttributesField::encode(READ_ONLY);
   __ Test(Operand(elements, scratch1, times_pointer_size,
                   kDetailsOffset - kHeapObjectTag),
           Smi::FromInt(kTypeAndReadOnlyMask));