worker: remove --experimental-worker flag

Having an experimental feature behind a flag makes change
if we are expecting significant breaking changes to its API.

Since the Worker API has been essentially stable since
its initial introduction, and no noticeable doubt about
possibly not keeping the feature around has been voiced,
removing the flag and thereby reducing the barrier to experimentation,
and consequently receiving feedback on the implementation,
seems like a good idea.

PR-URL: #25361
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Shingo Inoue <leko.noor@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Masashi Hirano <shisama07@gmail.com>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

lib/internal/bootstrap/loaders.js

@@ -255,8 +255,7 @@ if (config.exposeInternals) {
   };
 
   NativeModule.isInternal = function(id) {
-    return id.startsWith('internal/') ||
-        (id === 'worker_threads' && !config.experimentalWorker);
+    return id.startsWith('internal/');
   };
 }
 

lib/internal/bootstrap/node.js

@@ -179,9 +179,7 @@ function startup() {
     setupQueueMicrotask();
   }
 
-  if (getOptionValue('--experimental-worker')) {
-    setupDOMException();
-  }
+  setupDOMException();
 
   // On OpenBSD process.execPath will be relative unless we
   // get the full path before process.execPath is used.

lib/internal/modules/cjs/helpers.js

@@ -9,8 +9,6 @@ const {
   CHAR_HASH,
 } = require('internal/constants');
 
-const { getOptionValue } = require('internal/options');
-
 // Invoke with makeRequireFunction(module) where |module| is the Module object
 // to use as the context for the require() function.
 function makeRequireFunction(mod) {
@@ -100,14 +98,9 @@ const builtinLibs = [
   'dgram', 'dns', 'domain', 'events', 'fs', 'http', 'http2', 'https', 'net',
   'os', 'path', 'perf_hooks', 'punycode', 'querystring', 'readline', 'repl',
   'stream', 'string_decoder', 'tls', 'trace_events', 'tty', 'url', 'util',
-  'v8', 'vm', 'zlib'
+  'v8', 'vm', 'worker_threads', 'zlib'
 ];
 
-if (getOptionValue('--experimental-worker')) {
-  builtinLibs.push('worker_threads');
-  builtinLibs.sort();
-}
-
 if (typeof internalBinding('inspector').open === 'function') {
   builtinLibs.push('inspector');
   builtinLibs.sort();

src/node_config.cc

@@ -89,9 +89,6 @@ static void Initialize(Local<Object> target,
   if (env->options()->experimental_vm_modules)
     READONLY_TRUE_PROPERTY(target, "experimentalVMModules");
 
-  if (env->options()->experimental_worker)
-    READONLY_TRUE_PROPERTY(target, "experimentalWorker");
-
   if (env->options()->experimental_repl_await)
     READONLY_TRUE_PROPERTY(target, "experimentalREPLAwait");
 

src/node_options.cc

@@ -109,10 +109,7 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "experimental ES Module support in vm module",
             &EnvironmentOptions::experimental_vm_modules,
             kAllowedInEnvironment);
-  AddOption("--experimental-worker",
-            "experimental threaded Worker support",
-            &EnvironmentOptions::experimental_worker,
-            kAllowedInEnvironment);
+  AddOption("--experimental-worker", "", NoOp{}, kAllowedInEnvironment);
   AddOption("--expose-internals", "", &EnvironmentOptions::expose_internals);
   AddOption("--http-parser",
             "Select which HTTP parser to use; either 'legacy' or 'llhttp' "

src/node_options.h

@@ -96,7 +96,6 @@ class EnvironmentOptions : public Options {
   bool experimental_modules = false;
   bool experimental_repl_await = false;
   bool experimental_vm_modules = false;
-  bool experimental_worker = true;
   bool expose_internals = false;
   std::string http_parser =
 #ifdef NODE_EXPERIMENTAL_HTTP_DEFAULT