bug#44469: 27.1; Fontlock markup disappers when visual line is active

[Eli Zaretskii <eliz@gnu.org>]

> From: YH Tan <astyh83@gmail.com>
> Date: Fri, 6 Nov 2020 01:34:49 +0800
> 
> Can you advise me how to download that branch? 

  git clone https://git.savannah.gnu.org/git/emacs.git
  cd emacs
  git checkout emacs-27
  ./autogen.sh
  ./configure
  make

After this, you will have an Emacs executable in the src subdirectory;
invoke it and use it.

> Steps to reproduce the error are as follows: 
> 
> emacs -Q
> save scratch buffer as fontlock_issue.org in a convenient location
> paste sample text and switch to org-mode
> set line wrapping to word wrap
> evaluate the given elisp code
> revert buffer
> select (i.e. mark) the highlighted text
> 
> The behavior with emacs -Q is slightly different from what I experience. If the gif animation below works, you should see the highlighting on the third line of the Chinese text disappear as the cursor activates the entire line (seen as a paragraph in visual line mode). 

If this is related with highlighting of selected text, then it's
almost certainly bug#43363.