--- a/dom/base/nsDOMClassInfo.cpp
+++ b/dom/base/nsDOMClassInfo.cpp
@@ -6261,37 +6261,27 @@ ResolvePrototype(nsIXPConnect *aXPConnec
 
         if (JSVAL_IS_OBJECT(val)) {
           proto = JSVAL_TO_OBJECT(val);
         }
       }
     }
 
     if (dot_prototype) {
-      JSAutoEnterCompartment ac;
-      if (!ac.enter(cx, dot_prototype)) {
-        return NS_ERROR_UNEXPECTED;
-      }
-
       JSObject *xpc_proto_proto = ::JS_GetPrototype(cx, dot_prototype);
 
       if (proto &&
           (!xpc_proto_proto ||
            JS_GET_CLASS(cx, xpc_proto_proto) == sObjectClass)) {
         if (!JS_WrapObject(cx, &proto) ||
             !JS_SetPrototype(cx, dot_prototype, proto)) {
           return NS_ERROR_UNEXPECTED;
         }
       }
     } else {
-      JSAutoEnterCompartment ac;
-      if (!ac.enter(cx, winobj)) {
-        return NS_ERROR_UNEXPECTED;
-      }
-
       dot_prototype = ::JS_NewObject(cx, &sDOMConstructorProtoClass, proto,
                                      winobj);
       NS_ENSURE_TRUE(dot_prototype, NS_ERROR_OUT_OF_MEMORY);
     }
   }
 
   v = OBJECT_TO_JSVAL(dot_prototype);