[minor] Remove unnecessary optimization

It does not make much sense to optimize for empty messages.

Author: lpinca

lib/permessage-deflate.js

@@ -7,8 +7,6 @@ const bufferUtil = require('./buffer-util');
 const { kStatusCode, NOOP } = require('./constants');
 
 const TRAILER = Buffer.from([0x00, 0x00, 0xff, 0xff]);
-const EMPTY_BLOCK = Buffer.from([0x00]);
-
 const kPerMessageDeflate = Symbol('permessage-deflate');
 const kTotalLength = Symbol('total-length');
 const kCallback = Symbol('callback');
@@ -393,11 +391,6 @@ class PerMessageDeflate {
    * @private
    */
   _compress(data, fin, callback) {
-    if (!data || data.length === 0) {
-      process.nextTick(callback, null, EMPTY_BLOCK);
-      return;
-    }
-
     const endpoint = this._isServer ? 'server' : 'client';
 
     if (!this._deflate) {

test/sender.test.js

@@ -154,7 +154,7 @@ describe('Sender', () => {
 
           assert.strictEqual(chunks[0].length, 2);
           assert.strictEqual(chunks[0][0] & 0x40, 0x40);
-          assert.strictEqual(chunks[1].length, 1);
+          assert.strictEqual(chunks[1].length, 5);
 
           assert.strictEqual(chunks[2].length, 2);
           assert.strictEqual(chunks[2][0] & 0x40, 0x00);