WYSIWYG Full does not load on IE11

From directus created by michlschmitt : directus/directus#2031

Version Info

• Directus version and branch: 6.4.5. bundled version
• PHP version: PHP 7.0.25
• MySQL version: 5.5.58
• Web server: nginx
• OS name and version: Windows

Expected Behavior

Write an article via WYSIWYG Full Interface.

Actual Behavior

The WYSIWYG Full Editor does not show up on Windows and Internet Explorer 11.

Steps to Reproduce

1. Create a table with WYSIWYG Full field
2. Open the table and insert content if you can see the editor