Log Message:
Update Wordpress to 5.0.

On December 6, 2018, WordPress Version 5.0, named for jazz musician Bebo,
was released to the public. WordPress 5.0 will revolutionize content editing
with introduction of a new block editor and block editor-compatible default
theme Twenty Nineteen.

More infomations at https://wordpress.org/support/wordpress-version/version-5-0/