Don't internalize names that are array indexes since they aren't used for lookup (the index is)

src/lookup.cc

Index: src/lookup.cc
diff --git a/src/lookup.cc b/src/lookup.cc
index 83bfc79c8eefe6435b9134c33943e91f1d6bad83..1265d9056ea74f046584ebb21248a882c77bf9f0 100644
--- a/src/lookup.cc
+++ b/src/lookup.cc
@@ -38,7 +38,7 @@ LookupIterator LookupIterator::PropertyOrElement(Isolate* isolate,
     LookupIterator it(isolate, receiver, index, configuration);
     // Here we try to avoid having to rebuild the string later
     // by storing it on the indexed LookupIterator.
-    it.name_ = isolate->factory()->InternalizeName(name);
+    it.name_ = name;
     return it;
   }