Bug Description

The following logic in \AMP_Tag_And_Attribute_Sanitizer::sanitize_disallowed_attribute_values_in_node() is lacking:

Namely, a Mustache template can also be in a script tag that has type=text/plain and template=amp-mustache (see docs).

So anywhere that we are checking for a template tag we should also check for script with the required attributes. For example, in the form sanitizer:

Expected Behaviour

Mustache templates in template tags are treated the same as templates in script tags.

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Acceptance criteria

Implementation brief

QA testing instructions

Demo

Changelog entry