lib: hide navigator behind a flag

doc/api/globals.md

@@ -598,30 +598,32 @@ This variable may appear to be global but is not. See [`module`][].
 
 <!-- YAML
 added: v21.0.0
+changes:
+  version: REPLACEME
+  pr-url: https://github.com/nodejs/node/pull/50412
+  description: The API is behind the CLI flag `--experimental-global-navigator`.
 -->
 
-> Stability: 1.1 - Active development
+> Stability: 1.1 - Active development. Use `--experimental-global-navigator` to
+> enable this feature.
 
 A partial implementation of the [Navigator API][].
 
 ## `navigator`
 
 <!-- YAML
 added: v21.0.0
+changes:
+  version: REPLACEME
+  pr-url: https://github.com/nodejs/node/pull/50412
+  description: The API is behind the CLI flag `--experimental-global-navigator`.
 -->
 
-> Stability: 1.1 - Active development
+> Stability: 1.1 - Active development. Use `--experimental-global-navigator` to
+> enable this feature.
 
 A partial implementation of [`window.navigator`][].
 
-If your app or a dependency uses a check for `navigator` to determine whether it
-is running in a browser, the following can be used to delete the `navigator`
-global before app code runs:
-
-```bash
-node --import 'data:text/javascript,delete globalThis.navigator' app.js
-```
-
 ### `navigator.hardwareConcurrency`
 
 <!-- YAML

test/parallel/test-global.js

@@ -58,7 +58,6 @@ builtinModules.forEach((moduleName) => {
     'structuredClone',
     'fetch',
     'crypto',
-    'navigator',
   ];
   assert.deepStrictEqual(new Set(Object.keys(global)), new Set(expected));
 }

test/parallel/test-navigator.js

@@ -1,3 +1,4 @@
+// Flags: --experimental-global-navigator
 'use strict';
 
 require('../common');