Move internal modules to “internal” folder.

.internal/nodeUtil.js

@@ -0,0 +1,22 @@
+import freeGlobal from './.internal/freeGlobal.js';
+
+/** Detect free variable `exports`. */
+const freeExports = typeof exports == 'object' && exports && !exports.nodeType && exports;
+
+/** Detect free variable `module`. */
+const freeModule = freeExports && typeof module == 'object' && module && !module.nodeType && module;
+
+/** Detect the popular CommonJS extension `module.exports`. */
+const moduleExports = freeModule && freeModule.exports === freeExports;
+
+/** Detect free variable `process` from Node.js. */
+const freeProcess = moduleExports && freeGlobal.process;
+
+/** Used to access faster Node.js helpers. */
+const nodeUtil = ((() => {
+  try {
+    return freeProcess && freeProcess.binding && freeProcess.binding('util');
+  } catch (e) {}
+})());
+
+export default nodeUtil;