Make buttons respect display: none/contents in button layout

Fixes whatwg#10238. This matches what is already implemented in browsers.

source

@@ -134406,7 +134406,7 @@ input[type=image i][align=bottom i], object[align=bottom i] {
 
     <ul>
      <li><p>If the computed value of <span>'display'</span> is 'inline-grid', 'grid',
-     'inline-flex', or 'flex', then behave as the computed value.</p></li>
+     'inline-flex', 'flex', 'none', or 'contents', then behave as the computed value.</p></li>
 
      <li><p>Otherwise, if the computed value of <span>'display'</span> is a value such that the
      <span>outer display type</span> is 'inline', then behave as 'inline-block'.</p></li>
@@ -144046,6 +144046,7 @@ INSERT INTERFACES HERE
   Simon Sapin,
   Yu Han, <!-- yuzhe-han on GitHub -->
   Simon Spiegel,
+  Simon Wülker, <!-- Wuelle on GitHub -->
   skeww, <!-- on reddit -->
   Smylers,
   Srirama Chandra Sekhar Mogali,