events: re-use the same isTrusted getter

Creating a new function each time the property descriptor is set
comes with performance overhead, since these functions have different
identities, even if they contain the same code.

Refs: https://twitter.com/tverwaes/status/1285496612618473472

PR-URL: #34459
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>

Author: addaleax

lib/internal/event_target.js

@@ -7,6 +7,7 @@ const {
   Map,
   NumberIsInteger,
   Object,
+  ObjectDefineProperty,
   Symbol,
   SymbolFor,
   SymbolToStringTag,
@@ -57,6 +58,9 @@ const kTimestamp = Symbol('timestamp');
 const kBubbles = Symbol('bubbles');
 const kComposed = Symbol('composed');
 const kPropagationStopped = Symbol('propagationStopped');
+
+const isTrusted = () => false;
+
 class Event {
   constructor(type, options) {
     if (arguments.length === 0)
@@ -72,8 +76,8 @@ class Event {
     this[kTimestamp] = lazyNow();
     this[kPropagationStopped] = false;
     // isTrusted is special (LegacyUnforgeable)
-    Object.defineProperty(this, 'isTrusted', {
-      get() { return false; },
+    ObjectDefineProperty(this, 'isTrusted', {
+      get: isTrusted,
       enumerable: true,
       configurable: false
     });