[runtime] Stop cloning AccessorInfo, just rely on PropertyAttributes for readonly.

src/accessors.h

Index: src/accessors.h
diff --git a/src/accessors.h b/src/accessors.h
index 710e986b46b4c596f90aa612d2ab0a0b3641134a..4c8a0b2b7a9a33b0a75fc5a17c4efc9165728ddf 100644
--- a/src/accessors.h
+++ b/src/accessors.h
@@ -100,9 +100,6 @@ class Accessors : public AllStatic {
       AccessorNameGetterCallback getter,
       AccessorNameSetterCallback setter,
       PropertyAttributes attributes);
-
-  static Handle<AccessorInfo> CloneAccessor(Isolate* isolate,
-                                            Handle<AccessorInfo> accessor);
 };
 
 }  // namespace internal