Rework ES2015 module system and add missing features. (#2792)

Co-authored-by: Dániel Bátyai <dbatyai@inf.u-szeged.hu>
JerryScript-DCO-1.0-Signed-off-by: Dániel Bátyai dbatyai@inf.u-szeged.hu
JerryScript-DCO-1.0-Signed-off-by: Daniel Vince vinced@inf.u-szeged.hu

tests/jerry/es2015/module-import-03.js

@@ -0,0 +1,24 @@
+/* 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 incrementer, {aa, c_, x,} from "tests/jerry/es2015/module-export-03.js"
+var i = new incrementer(3);
+assert(i.incr() === 4);
+assert(i.incr() === 5);
+assert(i.incr() === 6);
+
+assert (aa === "a");
+assert (x === 42);
+assert (c_(x) == 84);