[runtime] Do not use the enum-cache for non-prototype objects.

src/elements.cc

Index: src/elements.cc
diff --git a/src/elements.cc b/src/elements.cc
index 16e8b067cf9273b15fc0dd291b4ad0471d47a721..839d833c945563b21409af80cb6814814ab2674b 100644
--- a/src/elements.cc
+++ b/src/elements.cc
@@ -1153,7 +1153,12 @@ class DictionaryElementsAccessor
         if (!AccessorInfo::cast(accessors)->all_can_read()) continue;
       }
       PropertyAttributes attr = details.attributes();
-      if ((attr & filter) != 0) continue;
+      if ((attr & filter) != 0) {
+        if (attr & PropertyAttributes::DONT_ENUM) {
+          keys->HideKey(index);
+        }
+        continue;
+      }
       keys->AddKey(index);
     }