there is strange problem: after blink update selector .groups .group:nth-child(2):nth-last-child(2){} just stop working.
But it still works well in webkit and gecko. Any ideas how to fix it?
HTML
<div class="groups">
    <div class="group"></div>
    <div class="group"></div>
    <div class="group"></div>
</div>
CSS
.groups .group{
    background-color:#000;
}
.groups .group:first-child{
    background-color:yellow;
}
.groups .group:nth-child(2):nth-last-child(2),
.groups .group:nth-child(2):last-child{
    background-color:red;
}
.groups .group:last-child:nth-child(3){
    background-color:green;
}
.groups{
    font-size:0;
}
.groups .group{
    display:inline-block;
    height:100px;
    width:30px;    
}
You may see how it work here: http://jsfiddle.net/LAq73/1/
How it work in blink (chrome): 
How it work in safari (webkit): 
And finaly FF:  
 
Any ideas how to fix it?
 
     
    