diff --git a/components/script/dom/webidls/Performance.webidl b/components/script/dom/webidls/Performance.webidl
index 0e2f7a960d5b..5db6551ff963 100644
--- a/components/script/dom/webidls/Performance.webidl
+++ b/components/script/dom/webidls/Performance.webidl
@@ -34,23 +34,20 @@ partial interface Performance {
   [Throws]
   void measure(DOMString measureName, optional DOMString startMark, optional DOMString endMark);
   void clearMeasures(optional DOMString measureName);
-
-
 };
+
 //https://w3c.github.io/resource-timing/#sec-extensions-performance-interface
 partial interface Performance {
   void clearResourceTimings ();
   void setResourceTimingBufferSize (unsigned long maxSize);
               attribute EventHandler onresourcetimingbufferfull;
 };
-// FIXME(avada): this should be deprecated, but is currently included for web compat
-// https://dvcs.w3.org/hg/webperf/raw-file/tip/specs/NavigationTiming/Overview.html#performance-timing-attribute
-[Exposed=(Window)]
-partial interface Performance {
-  PerformanceNavigationTiming timing();
-};
+
 // https://w3c.github.io/navigation-timing/#extensions-to-the-performance-interface
+[Exposed=Window]
 partial interface Performance {
-  [SameObject, Exposed=Window]
+  [SameObject]
+  readonly attribute PerformanceNavigationTiming timing;
+  [SameObject]
   readonly attribute PerformanceNavigation navigation;
 };