Drop performance from ShadowRealms.

Apparently it is no longer exposed there.

source

@@ -92275,11 +92275,6 @@ interface <dfn interface>BeforeUnloadEvent</dfn> : <span>Event</span> {
     fetched modules found in the principal realm's module map, so this map never contains entries
     which are null or "<code data-x="">fetching</code>".</p>
    </dd>
-
-   <dt><p>A <dfn data-x="synthetic-realm-settings-object-performance" for="synthetic realm settings
-   object"><code>Performance</code> object</dfn></p></dt>
-
-   <dd><p>A <code>Performance</code> object.</p></dd>
   </dl>
 
   <p><span data-x="synthetic realm">Synthetic realms</span> are created with <span data-x="global
@@ -96599,10 +96594,6 @@ import "https://example.com/foo/../module2.mjs";</code></pre>
    <li><p>Set <var>settings</var>'s <span data-x="synthetic-realm-settings-object-module-map">module
    map</span> to a new <span>module map</span>, initially empty.</p></li>
 
-   <li><p>Set <var>settings</var>'s <span
-   data-x="synthetic-realm-settings-object-performance"><code>Performance</code> object</span> to a
-   <span>new</span> <code>Performance</code> object in <var>realm</var>.</p></li>
-
    <li><p>Set <var>realm</var>.[[HostDefined]] to <var>settings</var>.</p></li>
 
    <li><p><span>Define the global property references</span> on <var>realm</var>.[[GlobalObject]],
@@ -96628,31 +96619,6 @@ import "https://example.com/foo/../module2.mjs";</code></pre>
 
    <li><p>Perform ! <span>DefinePropertyOrThrow</span>(<var>realm</var>.[[GlobalObject]], "self",
    <var>selfDescriptor</var>).</p></li>
-
-   <li>
-    <p>Let <var>performanceSteps</var> be the following series of steps:</p>
-
-    <ol>
-     <li><p>Let <var>thisValue</var> be the result of <span data-x="get the ShadowRealm global
-     object">getting the ShadowRealm global object</span> with <var>realm</var> and the <b>this</b>
-     value.</p></li>
-     <li><p>Return <var>thisValue</var>'s <span data-x="concept-global-object-realm">realm</span>'s
-     <span data-x="concept-realm-settings-object">environment settings object</span>'s <span
-     data-x="synthetic-realm-settings-object-performance"><code>Performance</code>
-     object</span>.</p></li>
-    </ol>
-   </li>
-
-   <li><p>Let <var>performanceGetter</var> be
-   <span>CreateBuiltinFunction</span>(<var>performanceSteps</var>, 0, "get performance", « »,
-   <var>realm</var>).</p></li>
-
-   <li><p>Let <var>performanceDescriptor</var> be the <span>PropertyDescriptor</span>{[[Get]]:
-   <var>performanceGetter</var>, [[Set]]: undefined, [[Enumerable]]: true, [[Configurable]]:
-   true}.</p></li>
-
-   <li><p>Perform ! <span>DefinePropertyOrThrow</span>(<var>realm</var>.[[GlobalObject]],
-   "performance", <var>performanceDescriptor</var>).</p></li>
   </ol>
 
   To <dfn>get the ShadowRealm global object</dfn> given <var>calleeRealm</var> and