<style> tag not being converted

[rrjanbiah]

When a HTML content contains style tag, it doesn't convert it. Few weird things happen:

1. $amp->convertToAmpHtml() completely removes style tag
2. But, $amp->warningsHumanText() displays error something like (from input string--not output string):

<style> on line 7
- The tag 'head > style[amp-boilerplate] - old variant' is deprecated - use 'head > style[amp-boilerplate]' instead.
   [code: DEPRECATED_TAG  category: DEPRECATION see: https://github.com/ampproject/amphtml/blob/master/spec/amp-boilerplate.md]

Context: Using $amp->loadHtml($html, ['scope' => Scope::HTML_SCOPE]);