Export default in namespace object (#4657)

Fix a crash when the exported value is a reference.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/jerry/es.next/module-namespace-01.mjs

@@ -0,0 +1,30 @@
+/* Copyright JS Foundation and other contributors, http://js.foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import * as o from "./module-namespace-02.mjs"
+import def from "./module-namespace-02.mjs"
+
+assert(o.default === 8.5)
+assert(def === 8.5)
+
+var val = {}
+
+assert(o.a === 2.5);
+assert(o.b === undefined);
+assert(o.c(val) === "c")
+assert(o.d === "d")
+
+assert(o.default === val)
+assert(def === val)