Always pass on a compare function to sort

src/ol/render/canvas/canvasimmediate.js

@@ -7,6 +7,7 @@ goog.provide('ol.render.canvas.Immediate');
 goog.require('goog.array');
 goog.require('goog.asserts');
 goog.require('goog.vec.Mat4');
+goog.require('ol.array');
 goog.require('ol.color');
 goog.require('ol.extent');
 goog.require('ol.geom.flat.transform');
@@ -721,7 +722,7 @@ ol.render.canvas.Immediate.prototype.drawText = goog.abstractMethod;
 ol.render.canvas.Immediate.prototype.flush = function() {
   /** @type {Array.<number>} */
   var zs = Object.keys(this.callbacksByZIndex_).map(Number);
-  zs.sort();
+  zs.sort(ol.array.defaultCompare);
   var i, ii, callbacks, j, jj;
   for (i = 0, ii = zs.length; i < ii; ++i) {
     callbacks = this.callbacksByZIndex_[zs[i].toString()];

src/ol/render/canvas/canvasreplay.js

@@ -2001,7 +2001,7 @@ ol.render.canvas.ReplayGroup.prototype.replay = function(
 
   /** @type {Array.<number>} */
   var zs = Object.keys(this.replaysByZIndex_).map(Number);
-  zs.sort();
+  zs.sort(ol.array.defaultCompare);
 
   // setup clipping so that the parts of over-simplified geometries are not
   // visible outside the current extent when panning