Check that Performance methods exist before invoking them (Dash-Industry-Forum#4831)

* addEventListener
* removeEventListener
* getEntriesByType

Author: steve-taylor

src/streaming/controllers/ThroughputController.js

@@ -70,23 +70,19 @@ function ThroughputController() {
     function _registerEvents() {
         eventBus.on(MediaPlayerEvents.METRIC_ADDED, _onMetricAdded, instance);
 
-        if (performance) {
-            performance.addEventListener(
-                'resourcetimingbufferfull',
-                _onResourceTimingBufferFull,
-            );
-        }
+        window.performance?.addEventListener?.(
+            'resourcetimingbufferfull',
+            _onResourceTimingBufferFull,
+        );
     }
 
     function _resetEvents() {
         eventBus.off(MediaPlayerEvents.METRIC_ADDED, _onMetricAdded, instance);
 
-        if (performance) {
-            performance.removeEventListener(
-                'resourcetimingbufferfull',
-                _onResourceTimingBufferFull,
-            );
-        }
+        window.performance?.removeEventListener?.(
+            'resourcetimingbufferfull',
+            _onResourceTimingBufferFull,
+        );
     }
 
     function _onResourceTimingBufferFull() {

src/streaming/net/HTTPLoader.js

@@ -501,7 +501,7 @@ function HTTPLoader(cfg) {
         }
 
         // Get a list of "resource" performance entries
-        const resources = performance.getEntriesByType('resource');
+        const resources = performance.getEntriesByType?.('resource');
         if (resources === undefined || resources.length <= 0) {
             return;
         }