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/class-inheritance-inner-class.js

@@ -0,0 +1,62 @@
+/* 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.
+ */
+
+// TODO: enable this test when super keyword is supported for normal functions
+/*
+var console = { assert : assert };
+
+class C1 {
+  f () {
+    return 5;
+  }
+}
+
+class C2 extends C1 {
+  f () {
+    assert (super.f () === 5);
+
+    class G {
+      g () {
+        assert (super.f === undefined);
+        assert (super.toString () === "[object Object]");
+        var a = super.valueOf ();
+        try {
+          a ();
+          assert (false);
+        } catch (e) {
+          assert (e instanceof TypeError);
+        }
+      }
+
+      constructor () {
+        // Test to overwrite the current lit-object
+        console.assert (Object.getPrototypeOf (this) === G.prototype);
+
+        try {
+          eval ("super ()");
+          assert (false);
+        } catch (e) {
+          assert (e instanceof SyntaxError);
+        }
+      }
+    }
+
+    var g = new G ();
+    g.g ();
+  }
+}
+
+(new C2).f ();
+*/