--- a/dom/animation/test/mozilla/file_restyling_xhr_doc.html
+++ b/dom/animation/test/mozilla/file_restyling_xhr_doc.html
@@ -97,23 +97,17 @@ promise_test(t => {
     // Adopt node into XHR doc
     xhrdoc.body.appendChild(div);
     // We should skip applying animation styles to elements in documents
     // without a pres shell.
     //
     // The Gecko style backend, however, does not do this. Since we expect the
     // Gecko style backend to be obsolete in the near future, we only perform
     // this check when the Servo backend is in use.
-    let isServo = false;
-    try {
-      isServo = SpecialPowers.getBoolPref('layout.css.servo.enabled');
-    } catch(e) {
-      // getBoolPref throws if the pref does not exist, in which case isServo
-      // should remain false.
-    }
+    let isServo = SpecialPowers.DOMWindowUtils.isStyledByServo;
     if (isServo) {
       assert_equals(getComputedStyle(div).opacity, '1',
                     'Style should NOT be updated');
     }
   });
 }, 'Moving an element with a pending animation restyle to a document without'
    + ' a browsing context resets animation style');