Tests that overriding shorthands within rule are visible.

[expanded] 
element.style { ()

[expanded] 
#main { (<style>…</style>)
/-- overloaded --/     -x: ;

[expanded] 
#main { (<style>…</style>)
/-- overloaded --/     -x: ;

[expanded] 
#main { (<style>…</style>)
/-- overloaded --/     background: #000;
    background: #bada55;

[expanded] 
div { (user agent stylesheet)
    display: block;