Re-target for ES.Next (#3901)

A list of changes:
- 'es2015-subset' profile is deprecated, and an 'es.next' profile is added.
- The default profile is changed to 'es.next'
- Renamed the JERRY_ES2015 guard to JERRY_ESNEXT
- Renamed JERRY_ES2015_BUILTIN_* guards to JERRY_BUILTIN_*
- Moved es2015 specific tests to a new 'es.next' subdirectory
- Updated docs, targets, and test runners to reflect these changes

Resolves #3737.

JerryScript-DCO-1.0-Signed-off-by: Dániel Bátyai dbatyai@inf.u-szeged.hu

tests/jerry/es.next/symbol-computed-object-literal.js

@@ -0,0 +1,38 @@
+/* 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.
+ */
+
+var symbolFoo = Symbol ('foo');
+var symbolBar = Symbol ('bar');
+
+var obj = {
+  _a : 5,
+  get [symbolFoo]() {
+    return this._a;
+  },
+  set [symbolFoo](a) {
+    this._a = a;
+  },
+  [symbolBar] : 10
+}
+
+/* Test accessor properties */
+assert (obj[symbolFoo] === 5);
+obj[symbolFoo] = 6;
+assert (obj[symbolFoo] === 6);
+
+/* Test nameddata properties */
+assert (obj[symbolBar] === 10);
+obj[symbolBar] = 20;
+assert (obj[symbolBar] === 20);