[parser] implement error reporting for Scanner errors

test/message/unicode-escape-undefined.js

Index: test/message/unicode-escape-undefined.js
diff --git a/test/message/regress/regress-4829-2.js b/test/message/unicode-escape-undefined.js
similarity index 82%
copy from test/message/regress/regress-4829-2.js
copy to test/message/unicode-escape-undefined.js
index eadb653a4b0f7a95dfc5faed6bf7bbd3370b8b8c..49de2fb2c814c14ed440a358b3d22c5dd41b982c 100644
--- a/test/message/regress/regress-4829-2.js
+++ b/test/message/unicode-escape-undefined.js
@@ -2,6 +2,4 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-function tag() {}
-
-`${tag`\xyy`}`;
+print("\u{110000}");