Extract nextTick to own file

lib/sinon/behavior.js

@@ -2,27 +2,14 @@
 
 var extend = require("./util/core/extend");
 var functionName = require("./util/core/function-name");
+var nextTick = require("./util/core/next-tick");
 var valueToString = require("./util/core/value-to-string");
 
 var slice = Array.prototype.slice;
 var join = Array.prototype.join;
 var useLeftMostCallback = -1;
 var useRightMostCallback = -2;
 
-var nextTick = (function () {
-    if (typeof process === "object" && typeof process.nextTick === "function") {
-        return process.nextTick;
-    }
-
-    if (typeof setImmediate === "function") {
-        return setImmediate;
-    }
-
-    return function (callback) {
-        setTimeout(callback, 0);
-    };
-})();
-
 function getCallback(behavior, args) {
     var callArgAt = behavior.callArgAt;
 

lib/sinon/util/core/next-tick.js

@@ -0,0 +1,20 @@
+"use strict";
+
+var hasNextTick = typeof process === "object" && typeof process.nextTick === "function";
+var hasSetImmediate = typeof setImmediate === "function";
+
+function nextTick(callback) {
+    setTimeout(callback, 0);
+}
+
+if (hasNextTick) {
+    module.exports = process.nextTick;
+}
+
+if (!hasNextTick && hasSetImmediate) {
+    module.exports = setImmediate;
+}
+
+if (!hasNextTick && !hasSetImmediate) {
+    module.exports = nextTick;
+}