background-size in shorthand background property CSS3

Question

I'm trying to mix background-image and background-size properties in a shorthanded background property. Based on W3C documentation background-size should come after background-position property separated with an slash(/).

W3C example:

p { background: url("chess.png") 40% / 10em gray
       round fixed border-box; } 

is equivalent to:

p {
    background-color: gray;
    background-position: 40% 50%;
    background-size: 10em 10em;
    background-repeat: round round;
    background-clip: border-box;
    background-origin: border-box;
    background-attachment: fixed;
    background-image: url(chess.png) }

MDN says same thing.

But this is not working! It also is not clear how to make a shorthand background property when background-size and background-position have two different values for background-position-x and background-position-y or same thing for background-size. It's not clear how the slash(/) takes place? 

Example I tried to make a shorthand is this CSS code:

div {  
    background: url(http://www.example.com/125/125) 
        0 0 /  150px 100px 
        repeat no-repeat 
        fixed border-box padding-box blue;      
    height: 300px;
    width:360px;    
    border: 10px dashed magenta;  
}

A cleaner example

This is working

 body{
        background-image:url(http://www.google.com/intl/en_com/images/srpr/logo3w.png);
        background-position:200px 100px;
        background-size:600px 400px;
        background-repeat:no-repeat;
    }

This is not working

body{
    background:url(http://www.google.com/intl/en_com/images/srpr/logo3w.png) 200px 100px/600px 400px no-repeat;
}

This is not working too

body{
    background:url(http://www.google.com/intl/en_com/images/srpr/logo3w.png) 200px/400px 100px/600px no-repeat;
}