Laravel dompdf khmer unicode not working correctly

Laravel 5.3.0

and https://github.com/barryvdh/laravel-dompdf

By default Khmer Unicode not support and then I follow instruction here

https://github.com/dompdf/dompdf/wiki/UnicodeHowTo

after complete Khmer Unicode characters not working correctly.

Result incorrect:

ខ្​ម​ែរយើង

What I want is :

ខ្មែរយើង