With >= 64 non-string instance types, I removed an optimization

src/x64/ic-x64.cc

Index: src/x64/ic-x64.cc
diff --git a/src/x64/ic-x64.cc b/src/x64/ic-x64.cc
index 22b403cb6bdaee60ed073fa2a3dc1e797ca84ebd..f26b234fed68c324b451c934cb50d568588e9aba 100644
--- a/src/x64/ic-x64.cc
+++ b/src/x64/ic-x64.cc
@@ -339,10 +339,10 @@ static void GenerateKeyNameCheck(MacroAssembler* masm,
 
   // Is the string internalized? We already know it's a string so a single
   // bit test is enough.
-  STATIC_ASSERT(kInternalizedTag != 0);
+  STATIC_ASSERT(kNotInternalizedTag != 0);
   __ testb(FieldOperand(map, Map::kInstanceTypeOffset),
-           Immediate(kIsInternalizedMask));
-  __ j(zero, not_unique);
+           Immediate(kIsNotInternalizedMask));
+  __ j(not_zero, not_unique);
 
   __ bind(&unique);
 }