Check for window.performance.mark

For compatibility with test environments that replace window.performance

Author: spicemix

src/performance/performance.service.ts

@@ -6,7 +6,7 @@ const IS_STABLE_START_MARK = '_isStableStart';
 const IS_STABLE_END_MARK = '_isStableEnd';
 
 function markStarts() {
-    if (typeof(window) !== 'undefined' && window.performance) {
+    if (typeof(window) !== 'undefined' && window.performance && window.performance.mark) {
         window.performance.mark(IS_STABLE_START_MARK);
         return true;
     } else {
@@ -22,7 +22,7 @@ export class PerformanceMonitoringService implements OnDestroy {
     private disposable: Subscription|undefined;
 
     constructor(appRef: ApplicationRef) {
-        if (started) {
+        if (started && window.performance.mark) {
             this.disposable = appRef.isStable.pipe(
                 first(it => it),
                 tap(() => {