Integrate with WebDriver BiDi user prompt handling

Each time we are about to pause for a user prompt, and after each pause, invoke the appropriate WebDriver BiDi algorithms.

source

@@ -4299,6 +4299,8 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-fragment-navigated">WebDriver BiDi fragment navigated</dfn></li>
      <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-dom-content-loaded">WebDriver BiDi DOM content loaded</dfn></li>
      <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-load-complete">WebDriver BiDi load complete</dfn></li>
+     <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-user-prompt-closed">WebDriver BiDi user prompt closed</dfn></li>
+     <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-user-prompt-opened">WebDriver BiDi user prompt opened</dfn></li>
     </ul>
    </dd>
 
@@ -91929,11 +91931,21 @@ dictionary <dfn dictionary>PageTransitionEventInit</dfn> : <span>EventInit</span
     <p>The user agent is encouraged to avoid asking the user for confirmation if it judges that
     doing so would be annoying, deceptive, or pointless.</p>
 
-    <p>If the user agent asks the user for confirmation, it must <span>pause</span> while waiting
-    for the user's response.</p>
+    <p>If the user agent asks the user for confirmation, it must:</p>
 
-    <p>If the user confirmed the page navigation, then set <var>result</var> to "<code
-    data-x="">confirm</code>"; otherwise return "<code data-x="">refuse</code>".</p>
+    <ol>
+     <li><p>Invoke <span>WebDriver BiDi user prompt opened</span> with <var>document</var>'s
+     <span>relevant global object</span>, "<code data-x="">beforeunload</code>", and "".</p></li>
+
+     <li><p><span>Pause</span> while waiting for the user's response.</p>
+
+     <li><p>If the user confirmed the page navigation, then set <var>result</var> to "<code
+     data-x="">confirm</code>"; otherwise to "<code data-x="">refuse</code>".</p>
+
+     <li><p>Invoke <span>WebDriver BiDi user prompt closed</span> with <var>document</var>'s
+     <span>relevant global object</span> and true if <var>result</var> is "<code
+     data-x="">confirm</code>" or false otherwise.</p></li>
+    </ol>
    </li>
 
    <li>
@@ -99741,8 +99753,14 @@ function sendData(data) {
 
    <li><p>Show <var>message</var> to the user, treating U+000A LF as a line break.</p></li>
 
+   <li><p>Invoke <span>WebDriver BiDi user prompt opened</span> with <span>this</span>,
+   "<code data-x="">alert</code>", and <var>message</var>.</p></li>
+
    <li><p>Optionally, <span>pause</span> while waiting for the user to acknowledge the
    message.</p></li>
+
+   <li><p>Invoke <span>WebDriver BiDi user prompt closed</span> with <span>this</span>
+   and true.</p></li>
   </ol>
 
   <p class="note">This method is defined using two overloads, instead of using an
@@ -99767,8 +99785,14 @@ function sendData(data) {
    <li><p>Show <var>message</var> to the user, treating U+000A LF as a line break, and ask the user
    to respond with a positive or negative response.</p></li>
 
+   <li><p>Invoke <span>WebDriver BiDi user prompt opened</span> with <span>this</span>,
+   "<code data-x="">confirm</code>", and <var>message</var>.</p></li>
+
    <li><p><span>Pause</span> until the user responds either positively or negatively.</p></li>
 
+   <li><p>Invoke <span>WebDriver BiDi user prompt closed</span> with <span>this</span>,
+   and true if the user responded positively or false otherwise.</p></li>
+
    <li><p>If the user responded positively, return true; otherwise, the user responded negatively:
    return false.</p></li>
   </ol>
@@ -99793,10 +99817,18 @@ function sendData(data) {
    to either respond with a string value or abort. The response must be defaulted to the value given
    by <var>default</var>.</p></li>
 
+   <li><p>Invoke <span>WebDriver BiDi user prompt opened</span> with <span>this</span>,
+   "<code data-x="">prompt</code>" and <var>message</var>.</p></li>
+
    <li><p><span>Pause</span> while waiting for the user's response.</p></li>
 
-   <li><p>If the user aborts, then return null; otherwise, return the string that the user responded
-   with.</p></li>
+   <li><p>Let <var>result</var> be null if the user aborts, or otherwise the string that the user
+   responded with.</p></li>
+
+   <li><p>Invoke <span>WebDriver BiDi user prompt closed</span> with <span>this</span>,
+   false if <var>result</var> is null or true otherwise, and <var>result</var>.</p></li>
+
+   <li><p>Return <var>result</var>.</li>
   </ol>
 
   <p>To <dfn>optionally truncate a simple dialog string</dfn> <var>s</var>, return either