buffer: revert toHex in favour of nbytes HexEncode update

Remove V8 Uint8Array.prototype.toHex() path for Buffer.toString('hex')
in favour of the upcoming nbytes HexEncode improvement (nodejs/nbytes#12)
which is ~3x faster through the existing C++ hexSlice path.

Refs: nodejs/nbytes#12

Author: thisalihassan

lib/buffer.js

@@ -51,20 +51,8 @@ const {
   TypedArrayPrototypeGetLength,
   TypedArrayPrototypeSet,
   Uint8Array,
-  Uint8ArrayPrototype,
-  uncurryThis,
 } = primordials;
 
-// Lazily initialized: toHex is installed by InitializeExperimentalGlobal()
-// (skipped during snapshot creation) and may be disabled with --no-js-base-64.
-let Uint8ArrayPrototypeToHex;
-function ensureUint8ArrayToHex() {
-  if (Uint8ArrayPrototypeToHex === undefined) {
-    Uint8ArrayPrototypeToHex = Uint8ArrayPrototype.toHex ?
-      uncurryThis(Uint8ArrayPrototype.toHex) : null;
-  }
-}
-
 const {
   byteLengthUtf8,
   compare: _compare,
@@ -682,18 +670,6 @@ function base64ByteLength(str, bytes) {
   return (bytes * 3) >>> 2;
 }
 
-function hexSliceToHex(buf, start, end) {
-  ensureUint8ArrayToHex();
-  // Fall back to C++ when toHex is unavailable or the result would exceed
-  // kStringMaxLength (so the correct ERR_STRING_TOO_LONG error is thrown).
-  if (Uint8ArrayPrototypeToHex === null || (end - start) * 2 > kStringMaxLength)
-    return hexSlice(buf, start, end);
-  return Uint8ArrayPrototypeToHex(
-    new Uint8Array(TypedArrayPrototypeGetBuffer(buf),
-                   TypedArrayPrototypeGetByteOffset(buf) + start,
-                   end - start));
-}
-
 const encodingOps = {
   utf8: {
     encoding: 'utf8',
@@ -771,7 +747,7 @@ const encodingOps = {
     encodingVal: encodingsMap.hex,
     byteLength: (string) => string.length >>> 1,
     write: hexWrite,
-    slice: hexSliceToHex,
+    slice: hexSlice,
     indexOf: (buf, val, byteOffset, dir) =>
       indexOfBuffer(buf,
                     fromStringFast(val, encodingOps.hex),