Add HTMLScriptElement.supports(type)

Closes #6472. See also the explainer at https://github.com/horo-t/explainers/blob/main/script_element_supports.md.

source

@@ -2944,7 +2944,8 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li>The terms <dfn data-x="concept-collection" data-x-href="https://dom.spec.whatwg.org/#concept-collection">collection</dfn> and <dfn data-x-href="https://dom.spec.whatwg.org/#represented-by-the-collection">represented by the collection</dfn></li>
 
      <li><dfn data-x-href="https://dom.spec.whatwg.org/#interface-domtokenlist"><code>DOMTokenList</code></dfn> interface, and its
-         <dfn data-x="dom-DOMTokenList-value" data-x-href="https://dom.spec.whatwg.org/#dom-domtokenlist-value"><code>value</code></dfn> attribute</li>
+         <dfn data-x="dom-DOMTokenList-value" data-x-href="https://dom.spec.whatwg.org/#dom-domtokenlist-value"><code>value</code></dfn> attribute and
+         <dfn data-x="dom-DOMTokenList-supports" data-x-href="https://dom.spec.whatwg.org/#dom-domtokenlist-supports"><code>supports</code></dfn> operation</li>
 
      <li><dfn data-x="dom-DOMImplementation-createDocument" data-x-href="https://dom.spec.whatwg.org/#dom-domimplementation-createdocument"><code>createDocument()</code></dfn> method</li>
      <li><dfn data-x="dom-DOMImplementation-createHTMLDocument" data-x-href="https://dom.spec.whatwg.org/#dom-domimplementation-createhtmldocument"><code>createHTMLDocument()</code></dfn> method</li>
@@ -58348,6 +58349,8 @@ interface <dfn interface>HTMLScriptElement</dfn> : <span>HTMLElement</span> {
   [<span>CEReactions</span>] attribute DOMString <span data-x="dom-script-integrity">integrity</span>;
   [<span>CEReactions</span>] attribute DOMString <span data-x="dom-script-referrerPolicy">referrerPolicy</span>;
 
+  static boolean <span data-x="dom-script-supports">supports</span>(DOMString type);
+
   // <a href="#HTMLScriptElement-partial">also has obsolete members</a>
 };</code></pre>
    </dd>
@@ -58570,6 +58573,14 @@ interface <dfn interface>HTMLScriptElement</dfn> : <span>HTMLElement</span> {
 
     <p>Can be set, to replace the element's children with the given value.</p>
    </dd>
+
+   <dt><code data-x=""><code>HTMLScriptElement</code>.<span subdfn data-x="dom-script-supports">supports</span>(<var>type</var>)</code></dt>
+
+   <dd>
+    <p>Returns true if the given <var>type</var> is a script type supported by the user agent.
+    The possible script types in this specification are "<code data-x="">classic</code>" and
+    "<code data-x="">module</code>", but others might be added in the future.
+   </dd>
   </dl>
 
   <div w-nodev>
@@ -58589,6 +58600,27 @@ interface <dfn interface>HTMLScriptElement</dfn> : <span>HTMLElement</span> {
   <code data-x="dom-innerHTML">innerHTML</code> and <code data-x="dom-outerHTML">outerHTML</code>
   attributes, they do not execute at all.</p>
 
+  <p>The <dfn method for="script"><code
+  data-x="dom-script-supports">supports(<var>type</var>)</code></dfn> method steps are:</p>
+
+  <ol>
+   <li><p>If <var>type</var> <span>is</span> "<code data-x="">classic</code>", then return
+   true.</p></li>
+
+   <li><p>If <var>type</var> <span>is</span> "<code data-x="">module</code>", then return
+   true.</p></li>
+
+   <li><p>Return false.</p></li>
+  </ol>
+
+  <p class="note">The <var>type</var> argument has to exactly match these values; we do not
+  <span>strip leading and trailing ASCII whitespace</span> or perform an <span>ASCII
+  case-insensitive</span> match. This is different from how <code
+  data-x="attr-script-type">type</code> content attribute values are treated, and how
+  <code>DOMTokenList</code>'s <code data-x="dom-DOMTokenList-supports">supports()</code> method
+  works, but it aligns with the <code>WorkerType</code> enumeration used in the <code
+  data-x="dom-Worker">Worker()</code> constructor.</p>
+
   <div class="example">
 
    <p>In this example, two <code>script</code> elements are used. One embeds an external
@@ -126970,6 +127002,7 @@ INSERT INTERFACES HERE
   Trey Eckels,
   triple-underscore, <!-- GitHub -->
   Tristan Fraipont, <!-- Kaiido on GitHub -->
+  保呂 毅 (Tsuyoshi Horo),
   Tyler Close,
   Valentin Gosu,
   Vardhan Gupta,