Retina icons are not rendered correctly by marker clusterer plus

[GoogleCodeExporter]

Retina icons on are rendered with the wrong size (2x).

As you are using MarkerClustererPlus see this fiddle here: 
http://jsfiddle.net/Rt28T/2/

This would be a viable fix (from the fiddle, thanks to the author of the 
fiddle):

ClusterIcon.prototype.show = function () {
if (this.div_) {
var img = "";
// NOTE: values must be specified in px units
var bp = this.backgroundPosition_.split(" ");
var spriteH = parseInt(bp[0].trim(), 10);
var spriteV = parseInt(bp[1].trim(), 10);
var pos = this.getPosFromLatLng_(this.center_);
this.div_.style.cssText = this.createCss(pos);
img = "";

Original issue reported on code.google.com by ckra...@comerge.net on 12 Jan 2015 at 8:16