blink: Open the preview-markdown and edit-markdown tab at the same page

[FoSuCloud]

Description

Open the preview-markdown and edit-markdown tab at the same page

Reproduce

1、create a markdown file
2、source code:

### a
sdsd

a fdsdsd
sdsdsdsadsadasd

sdsd

sdsd
11
sdsdsdasdsad
sdsdsdsdsd
sd
a

sdsdasdsad

### sddsd
    sdsds
    
    
asdas

3、As long as you use code syntax, it will cause flicker.
Use the syntax of the following link.
https://github.github.com/gfm/#example-3

Expected behavior

Context

• Operating System and version:
• Browser and version:
• JupyterLab version:
  max os 12.2
  Chrome 108
  JupyterLab v3.4.7

1、After editing, the code is executed
marked.marked()
2、debug in highlight

        setTimeout(() => {
          highlight(token.text, token.lang, function(err, code) {
            if (err) {
              return done(err);
            }
            if (code != null && code !== token.text) {
              token.text = code;
              token.escaped = true;
            }

            pending--;
            if (pending === 0) {
              done();
            }
          });
        }, 0);

3、after setTimeout,the page will blink

Troubleshoot Output

Paste the output from running `jupyter troubleshoot` from the command line here.
You may want to sanitize the paths in the output.

Command Line Output

Paste the output from your command line running `jupyter lab` here, use `--debug` if possible.

Browser Output

Paste the output from your browser Javascript console here, if applicable.

[krassowski]

This may be related to #13678.