meta_viewport rule fails to find viewport element inside block

[thibaudcolas]

Describe the bug

The base.html of the Django admin has a textbook accessibility fail – disabling zooming for mobile users: https://github.com/django/django/blob/278b6187d2a6711afb0b35dc5c3c09fe5be9adb3/django/contrib/admin/templates/admin/base.html#L15

This is what the meta_viewport rule is meant to pick up, unfortunately it doesn’t pick it up.

Which terms did you search for in the documentation and issue tracker?

viewport, meta, user-scalable

Environment

$ curlylint --version
curlylint, version 0.12.0

macOS Catalina

Steps to reproduce

1. Save https://github.com/django/django/blob/master/django/contrib/admin/templates/admin/base.html#L15 locally.
2. curlylint --rule 'meta_viewport: true' admin/templates/admin/base.html

Expected behavior

$ curlylint --rule 'meta_viewport: true' admin/templates/admin/base.html
admin/templates/admin/base.html
14:1	Remove `user-scalable=no` from the viewport meta so users can zoom	meta_viewport

Oh no! 💥 💔 💥
1 error reported

Actual behavior

$ curlylint --rule 'meta_viewport: true' admin/templates/admin/base.html
All done! ✨ 🍰 ✨

---

The problem seems to be with the meta tag being inside of a block:

{% block responsive %}
    <meta name="viewport" content="user-scalable=no, width=device-width, initial-scale=1.0, maximum-scale=1.0">
    <link rel="stylesheet" type="text/css" href="{% static "admin/css/responsive.css" %}">
    {% if LANGUAGE_BIDI %}<link rel="stylesheet" type="text/css" href="{% static "admin/css/responsive_rtl.css" %}">{% endif %}
{% endblock %}

Moving it out of the block, the issue is picked up correctly.