Add support for WebDriver BiDi language emulation

Add the required hook for the WebDriver BiDi spec w3c/webdriver-bidi#1017

Author: lutien

source

@@ -4697,6 +4697,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <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>
      <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-file-dialog-opened">WebDriver BiDi file dialog opened</dfn></li>
+     <li><dfn data-x-href="https://w3c.github.io/webdriver-bidi/#webdriver-bidi-emulated-language">WebDriver BiDi emulated language</dfn></li>
     </ul>
    </dd>
 
@@ -125529,19 +125530,37 @@ interface <dfn interface>Navigator</dfn> {
 
   <div algorithm>
   <p>The <dfn attribute for="NavigatorLanguage"><code
-  data-x="dom-navigator-language">language</code></dfn> getter steps are to return a valid BCP 47
-  language tag representing either <span>a plausible language</span> or the user's most preferred
-  language. <ref>BCP47</ref></p>
+  data-x="dom-navigator-language">language</code></dfn> getter steps are:</p>
+
+  <ol>
+   <li>Let <var>emulatedLanguage</var> be the <span>WebDriver BiDi emulated language</span> for
+   <span>this</span>'s <span>relevant settings object</span></li>
+
+   <li>If <var>emulatedLanguage</var> is not null, return <var>emulatedLanguage</var>.</li>
+
+   <li>Return a valid BCP 47 language tag representing either <span>a plausible language</span> or
+   the user's most preferred language. <ref>BCP47</ref>.</li>
+  </ol>
   </div>
 
   <div algorithm>
   <p>The <dfn attribute for="NavigatorLanguage"><code
-  data-x="dom-navigator-languages">languages</code></dfn> getter steps are to
-  return a <span>frozen array</span> of valid BCP 47 language tags representing either one
-  or more <span data-x="a plausible language">plausible languages</span>, or the user's preferred
-  languages, ordered by preference with the most preferred language first. The same object must be
-  returned until the user agent needs to return different values, or values in a different order.
-  <ref>BCP47</ref></p>
+  data-x="dom-navigator-languages">languages</code></dfn> getter steps are:</p>
+
+  <ol>
+   <li>Let <var>emulatedLanguage</var> be the <span>WebDriver BiDi emulated language</span> for
+   <span>this</span>'s <span>relevant settings object</span></li>
+
+   <li>If <var>emulatedLanguage</var> is not null, return a <span>frozen array</span> containing
+   <var>emulatedLanguage</var>.</li>
+
+   <li>Return a <span>frozen array</span> of valid BCP 47 language tags representing either one or
+   more <span data-x="a plausible language">plausible languages</span>, or the user's preferred
+   languages, ordered by preference with the most preferred language first. <ref>BCP47</ref></li>
+  </ol>
+
+  <p>The same object must be returned until the user agent needs to return different values, or
+  values in a different order, or <var>emulatedLanguage</var> is updated.</p>
   </div>
 
   <div algorithm>
@@ -155845,6 +155864,7 @@ INSERT INTERFACES HERE
   Abhishek Ghaskata,
   Abhishek Gupta, <!-- a1626 on GitHub -->
   Adam Barth,
+  Alexandra Borovova,
   Adam de Boor,
   Adam Hepton,
   Adam Klein,