Bug 1795933 - Remove now unnecessary and broken XUL workaround. r=mstange

Differential Revision: https://phabricator.services.mozilla.com/D159612

devtools/client/performance-new/popup/panel.jsm.js

@@ -129,9 +129,6 @@ function createViewControllers(state, elements) {
           preset.l10nIds.popup.description
         );
         elements.presetsMenuList.value = presetName;
-        // This works around XULElement height issues.
-        const { height } = elements.presetDescription.getBoundingClientRect();
-        elements.presetDescription.style.height = `${height}px`;
       } else {
         elements.presetDescription.style.display = "none";
         // We don't remove the l10n-id attribute as the element is hidden anyway.