Fix scanning bracketed expressions (#4964)

Scan 'async' literal with different depth of brackets

This patch fixes #4924.
This patch fixes #4748.

JerryScript-DCO-1.0-Signed-off-by: Martin Negyokru negyokru@inf.u-szeged.hu

tests/jerry/es.next/regression-test-issue-4924.js

@@ -0,0 +1,45 @@
+// 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.
+
+try {
+    eval(`async((a))`);
+    assert(false);
+}
+catch (e) {
+    assert(e instanceof ReferenceError);
+}
+
+try {
+    eval(`async(async((async((a)))))`);
+    assert(false);
+}
+catch (e) {
+    assert(e instanceof ReferenceError);
+}
+
+try {
+    eval(`async((a)`);
+    assert(false);
+}
+catch (e) {
+    assert(e instanceof SyntaxError);
+}
+
+try {
+    eval(`async((a)))`);
+    assert(false);
+}
+catch (e) {
+    assert(e instanceof SyntaxError);
+}