perf: add toJSON to performance class

Added toJSON method to the InternalPerformance class as per the
convention followed in other performance classes and per the spec:
https://www.w3.org/TR/hr-time/#tojson-method

Fixes: nodejs#37623

Author: yashLadha

lib/perf_hooks.js

@@ -59,6 +59,14 @@ class Performance extends EventTarget {
       timeOrigin: this.timeOrigin,
     }, opts)}`;
   }
+
+  toJSON() {
+    return {
+      nodeTiming: this.nodeTiming.toJSON(),
+      timeOrigin: this.timeOrigin,
+      eventLoopUtilization: this.eventLoopUtilization()
+    };
+  }
 }
 
 class InternalPerformance extends EventTarget {}
@@ -114,7 +122,7 @@ module.exports = {
   PerformanceObserver,
   monitorEventLoopDelay,
   createHistogram,
-  performance: new InternalPerformance(),
+  performance: new InternalPerformance()
 };
 
 ObjectDefineProperty(module.exports, 'constants', {