fix event removal in diff

fix CI

test-utils/callAsync.js

@@ -1,57 +1,3 @@
 "use strict"
 
-/**
- * This is modeled after Bluebird's scheduler. It solves for quite a few edge
- * cases, and should help alleviate most of the flakiness issues. It also speeds
- * up the suite a bit.
- */
-
-module.exports = (function () {
-	// The scheduler for NodeJS/io.js is setImmediate for recent versions of
-	// node because of macrotask semantics (i.e. don't starve the event loop).
-	if (typeof process !== "undefined" &&
-			/^\[object process\]/i.test({}.toString.call(process))) {
-		var version = process.versions.node.split(".").map(Number)
-		var isRecent = version[0] === 0 && version[1] > 10 || version[0] > 0
-
-		return isRecent ? setImmediate : process.nextTick
-	}
-
-	if (typeof Promise === "function") {
-		var p = Promise.resolve()
-
-		return function (fn) {
-			p.then(fn)
-		}
-	}
-
-	if (typeof MutationObserver !== "undefined") {
-		// Using 2 mutation observers to batch multiple updates into one.
-		var div = document.createElement("div")
-		var opts = {attributes: true}
-		var toggleScheduled = false
-		var div2 = document.createElement("div")
-		var o2 = new MutationObserver(function() {
-			div.classList.toggle("foo")
-			toggleScheduled = false
-		})
-		o2.observe(div2, opts)
-
-		function scheduleToggle() {
-			if (toggleScheduled) return
-			toggleScheduled = true
-			div2.classList.toggle("foo")
-		}
-
-		return function (fn) {
-			var o = new MutationObserver(function() {
-				o.disconnect()
-				fn()
-			})
-			o.observe(div, opts)
-			scheduleToggle()
-		}
-	}
-
-	return typeof setImmediate === "function" ? setImmediate : setTimeout
-})()
+module.exports = typeof setImmediate === "function" ? setImmediate : setTimeout