fix: custom inspect should not throw when called with wrong this

lib/internal/event_target.js

@@ -867,8 +867,6 @@ class EventTarget {
     return new CustomEvent(type, { detail: nodeValue });
   }
   [customInspectSymbol](depth, options) {
-    if (!isEventTarget(this))
-      throw new ERR_INVALID_THIS('EventTarget');
     const name = this.constructor.name;
     if (depth < 0)
       return name;

test/parallel/test-eventtarget-custom-inspect-does-not-throw.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const assert = require('assert');
+const util = require('util');
+
+const symbol = util.inspect.custom;
+
+const eventTargetInspect = EventTarget.prototype[symbol];
+
+const fakeEventTarget = {
+  [symbol]: eventTargetInspect,
+  someOtherField: 42
+};
+
+assert.doesNotThrow(() => {
+  util.inspect(fakeEventTarget);
+});