Add showPicker to <select> elements

Closes whatwg#7957

source

@@ -52758,6 +52758,8 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   boolean <span data-x="dom-cva-reportValidity">reportValidity</span>();
   undefined <span data-x="dom-cva-setCustomValidity">setCustomValidity</span>(DOMString error);
 
+  undefined <span data-x="dom-select-showPicker">showPicker</span>();
+
   readonly attribute <span>NodeList</span> <span data-x="dom-lfe-labels">labels</span>;
 };</code></pre>
    </dd>
@@ -53085,6 +53087,21 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
 
     <p>Can be set, to change the selection.</p>
    </dd>
+
+   <dt><code data-x=""><var>select</var>.<span subdfn data-x="dom-select-showPicker">showPicker</span>()</code></dt>
+
+   <dd>
+    <p>Shows any applicable picker UI for <var>select</var>, so that the user can select a value.
+
+    <p>Throws an <span>"<code>InvalidStateError</code>"</span> <code>DOMException</code> if
+    <var>select</var> is not <span data-x="concept-fe-mutable">mutable</span>.</p>
+
+    <p>Throws a <span>"<code>NotAllowedError</code>"</span> <code>DOMException</code> if called
+    without <span data-x="transient activation">transient user activation</span>.</p>
+
+    <p>Throws a <span>"<code>SecurityError</code>"</span> <code>DOMException</code> if
+    <var>select</var> is inside a cross-origin <code>iframe</code>.</p>
+   </dd>
   </dl>
 
   <div w-nodev>
@@ -53095,6 +53112,27 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   data-x="">select-multiple</code>" if the <code data-x="attr-select-multiple">multiple</code>
   attribute is present.</p>
 
+  <p>The <dfn method for="HTMLSelectElement"><code
+  data-x="dom-select-showPicker">showPicker()</code></dfn> method steps are:</p>
+
+  <ol>
+   <li><p>If <span>this</span> is not <span data-x="concept-fe-mutable">mutable</span>, then throw
+   an <span>"<code>InvalidStateError</code>"</span> <code>DOMException</code>.</p></li>
+
+   <li>
+    <p>If <span>this</span>'s <span>relevant settings object</span>'s <span
+    data-x="concept-settings-object-origin">origin</span> is not <span>same origin</span> with
+    <span>this</span>'s <span>relevant settings object</span>'s <span>top-level origin</span>, then throw a
+    <span>"<code>SecurityError</code>"</span> <code>DOMException</code>.</p>
+   </li>
+
+   <li><p>If <span>this</span>'s <span>relevant global object</span> does not have <span>transient
+   activation</span>, then throw a <span>"<code>NotAllowedError</code>"</span>
+   <code>DOMException</code>.</p></li>
+
+   <li><p>Show the picker, if applicable, for <span>this</span>.</p></li>
+  </ol>
+
   <p>The <dfn attribute for="HTMLSelectElement"><code
   data-x="dom-select-options">options</code></dfn> IDL attribute must return an
   <code>HTMLOptionsCollection</code> rooted at the <code>select</code> node, whose filter matches
@@ -139684,6 +139722,7 @@ INSERT INTERFACES HERE
   Lucas Gadani,
   &#x0141;ukasz Pilorz,
   Luke Kenneth Casson Leighton,
+  Luke Warlow,
   Luke Wilde,
   Maciej Stachowiak,
   Magne Andersson,