When using backspace key to delete first multi-byte character inside macros, also delete macro itself with Chrome.

How to reproduce

1. Create page and insert panel macro.
2. Input Japanese character. macro_issue1.png
3. Delete the first character with backspace key before defining the character and the panel itself is also removed. macro_issue2.png

Description

• With the other browsers (IE11, FireFox) the phenomenon hasn't occured.
• In 3, if after defining the characters and removing the underline (macro_issue3.png), the panel macro is not removed.
• This phenomenon occurs with other macros (Code block macro, Info macro,,,).