util: move getConstructorOf() to internal

PR-URL: https://github.com/nodejs/node/pull/12526
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/util.js

@@ -180,6 +180,21 @@ function convertToValidSignal(signal) {
   throw new Error('Unknown signal: ' + signal);
 }
 
+function getConstructorOf(obj) {
+  while (obj) {
+    var descriptor = Object.getOwnPropertyDescriptor(obj, 'constructor');
+    if (descriptor !== undefined &&
+        typeof descriptor.value === 'function' &&
+        descriptor.value.name !== '') {
+      return descriptor.value;
+    }
+
+    obj = Object.getPrototypeOf(obj);
+  }
+
+  return null;
+}
+
 module.exports = exports = {
   assertCrypto,
   cachedResult,
@@ -188,6 +203,7 @@ module.exports = exports = {
   decorateErrorStack,
   deprecate,
   filterDuplicateStrings,
+  getConstructorOf,
   isError,
   normalizeEncoding,
   objectToString,

lib/util.js

@@ -278,22 +278,6 @@ function arrayToHash(array) {
 }
 
 
-function getConstructorOf(obj) {
-  while (obj) {
-    var descriptor = Object.getOwnPropertyDescriptor(obj, 'constructor');
-    if (descriptor !== undefined &&
-        typeof descriptor.value === 'function' &&
-        descriptor.value.name !== '') {
-      return descriptor.value;
-    }
-
-    obj = Object.getPrototypeOf(obj);
-  }
-
-  return null;
-}
-
-
 function ensureDebugIsInitialized() {
   if (Debug === undefined) {
     const runInDebugContext = require('vm').runInDebugContext;
@@ -410,7 +394,7 @@ function formatValue(ctx, value, recurseTimes) {
     });
   }
 
-  var constructor = getConstructorOf(value);
+  var constructor = internalUtil.getConstructorOf(value);
 
   // Some type of object without properties can be shortcutted.
   if (keys.length === 0) {