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/let14.js

@@ -0,0 +1,54 @@
+// 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.
+
+function f() { return 4 }
+
+exit: {
+  assert(f() === 6);
+  break exit;
+  function f() { return 6; }
+}
+assert(f() === 4);
+
+{
+  assert(f() === 6);
+  f = 1;
+  assert(f === 1);
+  function f() { return 6; }
+  f = 2;
+  assert(f === 2);
+}
+assert(f === 1);
+
+function g() { return 3 }
+exit: {
+  assert(g() === 5);
+  function g() { return 4; }
+  break exit;
+  function g() { return 5; }
+}
+assert(g() === 5);
+
+function h() {
+  try {
+    x;
+    assert(false);
+  } catch (e) {
+    assert(e instanceof ReferenceError);
+  }
+
+  eval("exit: { assert(x() === 8); x = 4; break exit; function x() { return 8; } }");
+  assert(x === undefined);
+}
+h();