lib: move duplicate spliceOne into internal/util

lib/url.js and lib/events.js are using the same spliceOne function.
This change is to move it into the internal/util for avoiding duplicate
code.

Author: starkwang

lib/events.js

@@ -22,6 +22,7 @@
 'use strict';
 
 var domain;
+var spliceOne;
 
 function EventEmitter() {
   EventEmitter.init.call(this);
@@ -416,8 +417,11 @@ EventEmitter.prototype.removeListener =
 
         if (position === 0)
           list.shift();
-        else
+        else {
+          if (spliceOne === undefined)
+            spliceOne = require('internal/util').spliceOne;
           spliceOne(list, position);
+        }
 
         if (list.length === 1)
           events[type] = list[0];
@@ -529,13 +533,6 @@ EventEmitter.prototype.eventNames = function eventNames() {
   return this._eventsCount > 0 ? Reflect.ownKeys(this._events) : [];
 };
 
-// About 1.5x faster than the two-arg version of Array#splice().
-function spliceOne(list, index) {
-  for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
-    list[i] = list[k];
-  list.pop();
-}
-
 function arrayClone(arr, n) {
   var copy = new Array(n);
   for (var i = 0; i < n; ++i)

lib/internal/util.js

@@ -271,6 +271,13 @@ function join(output, separator) {
   return str;
 }
 
+// About 1.5x faster than the two-arg version of Array#splice().
+function spliceOne(list, index) {
+  for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
+    list[i] = list[k];
+  list.pop();
+}
+
 module.exports = {
   assertCrypto,
   cachedResult,
@@ -281,10 +288,11 @@ module.exports = {
   filterDuplicateStrings,
   getConstructorOf,
   isError,
+  join,
   normalizeEncoding,
   objectToString,
   promisify,
-  join,
+  spliceOne,
 
   // Symbol used to customize promisify conversion
   customPromisifyArgs: kCustomPromisifyArgsSymbol,

lib/url.js

@@ -28,6 +28,8 @@ const { hexTable } = require('internal/querystring');
 
 const errors = require('internal/errors');
 
+const { spliceOne } = require('internal/util');
+
 // WHATWG URL implementation provided by internal/url
 const {
   URL,
@@ -952,13 +954,6 @@ Url.prototype.parseHost = function parseHost() {
   if (host) this.hostname = host;
 };
 
-// About 1.5x faster than the two-arg version of Array#splice().
-function spliceOne(list, index) {
-  for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
-    list[i] = list[k];
-  list.pop();
-}
-
 // These characters do not need escaping:
 // ! - . _ ~
 // ' ( ) * :