Error loading TinyMCE scripts through wp-tinymce.php

[jeremyfelt]

Describe the bug

Some servers may expect that TinyMCE is loaded with static JavaScript files rather than wp-tinymce.php.

In WordPress core, TinyMCE is loaded as "compressed" via wp-tinymce.php or uncompressed (?) via tinymce.min.js depending on a handful of conditions.

I haven't tracked down the conditions that are causing my server to request the uncompressed version, but I do know that at some point I applied an Nginx configuration that blocks direct access to PHP files in wp-includes/ and wp-admin/includes/. As of Gutenberg 3.0.0, the TinyMCE script results in a 403 forbidden and the editor doesn't work.

My guess is that this problem will go away when Gutenberg is merged into core, but in the meantime it may be good to use the same logic from class-wp-editor.php to load TinyMCE.

To Reproduce
Steps to reproduce the behavior:

1. define( 'COMPRESS_SCRIPTS', false );
2. Block public access to wp-includes/*.php
3. Open new post screen.
4. Click in first paragraph block.
5. See error.

Expected behavior
I'd expect to be able to leave my server configuration the same and access the editor.

Additional context

• Gutenberg 3.0.0
• WordPress 4.9.6