lib: move process prototype manipulation into setupProcessObject

Since no operation is requiring process to be an EventEmitter before
setupProcessObject is called, it's safe to set up the prototype chain
in setupProcessObject and make the main code path more readable.

PR-URL: #24089
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/internal/bootstrap/node.js

@@ -28,13 +28,6 @@
   const isMainThread = internalBinding('worker').threadId === 0;
 
   function startup() {
-    const EventEmitter = NativeModule.require('events');
-
-    const origProcProto = Object.getPrototypeOf(process);
-    Object.setPrototypeOf(origProcProto, EventEmitter.prototype);
-
-    EventEmitter.call(process);
-
     setupProcessObject();
 
     // Do this good and early, since it handles errors.
@@ -335,6 +328,11 @@
   }
 
   function setupProcessObject() {
+    const EventEmitter = NativeModule.require('events');
+    const origProcProto = Object.getPrototypeOf(process);
+    Object.setPrototypeOf(origProcProto, EventEmitter.prototype);
+    EventEmitter.call(process);
+
     _setupProcessObject(pushValueToArray);
 
     function pushValueToArray() {