Update interfaces/user-timing.idl (#16552)

Source: https://github.com/tidoust/reffy-reports/blob/37bffd8/whatwg/idl/user-timing.idl
Build: https://travis-ci.org/tidoust/reffy-reports/builds/524800801
diff --git a/interfaces/user-timing.idl b/interfaces/user-timing.idl
index cd2e144..13ad7f8 100644
--- a/interfaces/user-timing.idl
+++ b/interfaces/user-timing.idl
@@ -4,12 +4,12 @@
 // Source: User Timing Level 3 (https://w3c.github.io/user-timing/)
 
 dictionary PerformanceMarkOptions {
-    any detail = null;
+    any detail;
     DOMHighResTimeStamp startTime;
 };
 
 dictionary PerformanceMeasureOptions {
-    any detail = null;
+    any detail;
     (DOMString or DOMHighResTimeStamp) start;
     DOMHighResTimeStamp duration;
     (DOMString or DOMHighResTimeStamp) end;
@@ -18,7 +18,7 @@
 partial interface Performance {
     PerformanceMark mark(DOMString markName, optional PerformanceMarkOptions markOptions);
     void clearMarks(optional DOMString markName);
-    PerformanceMeasure measure(DOMString measureName, optional (DOMString or PerformanceMeasureOptions)? startOrMeasureOptions, optional DOMString endMark);
+    PerformanceMeasure measure(DOMString measureName, optional (DOMString or PerformanceMeasureOptions) startOrMeasureOptions, optional DOMString endMark);
     void clearMeasures(optional DOMString measureName);
 };