--TEST--
Test margin optimization
--CSS--
a { 
    margin-left: 10px;
    margin-right: 10px;
    margin-top: 10px;
    margin-bottom: 10px;
}
b {
    margin-left: 6px;
    margin-right: 6px;
    margin-top: 10px;
    margin-bottom: 10px;
}
c {
    margin-left: 6px;
    margin-right: 6px;
    margin-top: 10px;
    margin-bottom: 1px;
}
d {
    margin-left: 1px;
    margin-right: 6px;
    margin-top: 10px;
    margin-bottom: 3px;
}
--EXPECT--
array (
  'a' => 
  array (
    'margin' => '10px',
  ),
  'b' => 
  array (
    'margin' => '10px 6px',
  ),
  'c' => 
  array (
    'margin' => '10px 6px 1px',
  ),
  'd' => 
  array (
    'margin' => '10px 6px 3px 1px',
  ),
)