add step for upgrades, still missing fallback

Author: carlosjoan91

fetch.bs

@@ -2121,6 +2121,9 @@ Unless stated otherwise, it is false.
 
 <p class=note>This flag is for exclusive use by HTML's render-blocking mechanism. [[!HTML]]
 
+<p>A <a for=/>request</a> has an associated boolean <dfn export for=request>https-upgrade</dfn>.
+Unless stated otherwise, it it false.
+
 <hr>
 
 <p>A <a for=/>request</a> has an associated
@@ -4405,6 +4408,11 @@ steps:
 
  <li><p><a>Upgrade <var>request</var> to a potentially trustworthy URL, if appropriate</a>.
 
+ <li><p>If <var>request</var> is a <a>navigation request</a>, and <var>request</var>'s
+ <a for=request>URL</a> is not a <a>potentially trustworthy URL</a>, optionally upgrade it to a
+ <a>potentially trustworthy URL<a>. If <var>request</var> is upgraded, set <var>request</var>'s
+ <a for=request>https-upgrade</a> flag to true.
+
  <li><p><a>Upgrade a mixed content <var>request</var> to a potentially trustworthy URL, if appropriate</a>.
 
  <li><p>If <a lt="block bad port">should <var>request</var> be blocked due to a bad port</a>,