ReStructuredText files have no syntax highlight for source view

Summary

ReStructuredText files have broken syntax highlight for source view

Steps to reproduce

1. Create *.rst file with code-block and specify language.
2. Open it in and ensure to select "Display source" option.

Example Project

Here is the project and reproducing file: link

What is the current bug behavior?

No syntax highlighting applied. Document title should be highlighted and code inside the code-block too.

What is the expected correct behavior?

Syntax highlighting is applied.

Output of checks

This bug happens on GitLab.com