util: runtime deprecation util.isBuffer

PR-URL: #50488
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Yagiz Nizipli <yagiz.nizipli@sentry.io>
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

doc/api/deprecations.md

@@ -1011,6 +1011,9 @@ The [`util.isBoolean()`][] API is deprecated.
 
 <!-- YAML
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/50488
+    description: Runtime deprecation.
   - version:
     - v6.12.0
     - v4.8.6
@@ -1023,7 +1026,7 @@ changes:
     description: Documentation-only deprecation.
 -->
 
-Type: Documentation-only
+Type: Runtime
 
 The [`util.isBuffer()`][] API is deprecated. Please use
 [`Buffer.isBuffer()`][] instead.

lib/util.js

@@ -394,7 +394,9 @@ module.exports = {
   isBoolean: deprecate(isBoolean,
                        'The `util.isBoolean` API is deprecated.  Please use `typeof arg === "boolean"` instead.',
                        'DEP0045'),
-  isBuffer: deprecate(isBuffer, 'The `util.isBuffer API is deprecated.', 'DEP0046'),
+  isBuffer: deprecate(isBuffer,
+                      'The `util.isBuffer` API is deprecated. Please use `Buffer.isBuffer()` instead.',
+                      'DEP0046'),
   isDeepStrictEqual(a, b) {
     if (internalDeepEqual === undefined) {
       internalDeepEqual = require('internal/util/comparisons')