Remove IE Compat scripts from Media element scripting

[joedolson]

WordPress injects scripts to create elements if the user is on IE less than 9 in wp_playlist_scripts(), wp_audio_shortcode(), and wp_video_shortcode().

It's time to remove these.

See #24902.

Trac ticket: https://core.trac.wordpress.org/ticket/63471

[aslamdoctor]

It is done now and PR has been created.

The phpunit tests need to be updated to stop looking for the conditional IE addition. For example: ​https://github.com/WordPress/wordpress-develop/blob/8c011572459ef6353182f444f86adf244833f902/tests/phpunit/tests/media.php#L1002

Thanks @mindctrl
It is done now 🙂

[nigelnelles]

We reproduced the error by adding a shortcode block to the site with the following code:

[video src="​https://example.com/video.mp4" poster="​https://example.com/poster.jpg" width="800" height="450" autoplay="true"]

With this shortcode on the site, the elements tab in the devtools shows:

<!--[if lt IE 9]><script>document.createElement('video');</script><![endif]-->

When doing the same thing on the playground generated from the PR, this comment is not present which is the goal of the PR

[desrosj]

In 60285:

Media: Remove inline scripts targeting IE < 9.

In #24902, an inline script was introduced to wp_playlist_scripts(), wp_audio_shortcode(), and wp_video_shortcode() for HTML5 compatibility in browsers running IE 8 and earlier.

These browsers have long been unsupported by WordPress, and unsupported by Microsoft for 9 years or more. So this compatibility code is no longer necessary and can safely be removed.

Hit the road, Jack, and don't ya come back no more, no more, no more, no more!

Props aslamdoctor, mindctrl, nigelnelles, joedolson.
Fixes #63471.

Thanks for the PR! This was merged in r60285.