GitLab

Augments type context and adds grammatical rules to handle special HTML constructs:
    <!-- comments -->
    <script>raw text</script>
    <textarea>no tags here</textarea>

This CL does not elide comment content.  I recommend we do that but
have not done it in this CL.

I used a codesearch tool over a codebase in another template language.

Based on the below I think we should definitely recognize
  <script>, <style>, <textarea>, and <title>
as each of these appears frequently enough that there are few
template using apps that do not use most of them.

Of the other special tags,
  <xmp>, <noscript>
are used but infrequently, and
  <noframe> and friend, <listing>
do not appear at all.

We could support <xmp> even though it is obsolete in HTML5
because we already have the machinery, but I suggest we do not
support noscript since it is a normal tag in some browser
configurations.

I suggest recognizing and eliding <!-- comments -->
(but n...