Fix whatwg#245 - Addressing new popover values

Since the popover attribute got a new value, it's
"find topmost popover ancestor" algorithm changed, and this PR
attempts to address this in the Fullscreen API specification.

After discussing with Luke Warlow we came to the conclusion
that this is probably the intended change for the Fullscreen API spec.

Author: theIDinside

fullscreen.bs

@@ -11,6 +11,11 @@ Markup Shorthands: css no
 </pre>
 
 <pre class=link-defaults>
+spec:html
+    type:dfn; text:allowed to use
+    type:dfn; text:showing hint popover list
+    type:dfn; text:showing auto popover list
+
 spec:dom
     type:dfn; for:/; text:document
     type:dfn; for:/; text:element
@@ -69,11 +74,16 @@ is an <a>ordered set</a> of (<a>string</a>, <a>element</a>) <a>tuples</a>. It is
 <p>To <dfn>fullscreen an <var>element</var></dfn>:
 
 <ol>
+ <li><p>Let <var>document</var> be <var>element</var>'s <a>node document</a>.
+
  <li><p>Let <var>hideUntil</var> be the result of running <a>topmost popover ancestor</a> given
- <var>element</var>, null, and false.
+ <var>element</var>, <var>document</var>'s <a>showing hint popover list</a>, null, and false.
+
+ <li><p>If <var>hideUntil</var> is null, then set <var>hideUntil</var> to the result of running
+ topmost popover ancestor, given <var>element</var>, <var>document</var>'s <a>showing auto popover
+ list</a>, null, and false.
 
- <li><p>If <var>hideUntil</var> is null, then set <var>hideUntil</var> to <var>element</var>'s
- <span>node document</span>.
+ <li><p>If <var>hideUntil</var> is null, then set <var>hideUntil</var> to <var>document</var>.
 
  <li><p>Run <a>hide all popovers until</a> given <var>hideUntil</var>, false, and true.
 
@@ -725,6 +735,7 @@ Rafał Chłodnicki,
 Riff Jiang,
 Rune Lillesveen,
 Sigbjørn Vik,
+Simon Farre,
 Simon Pieters,
 Tab Atkins-Bittner,
 Takayoshi Kochi,