Support values ending in !important

[Krinkle]

Input:

.foo {
  left: 10px !important;
  float: left !important;
  padding: 1px 2px 3px 4px !important;
}

Expected:

.foo {
  right: 10px !important;
  float: right !important;
  padding: 1px 4px 3px 2px !important;
}

Actual:

.foo {
  right: 10px !important;
  float: right !important;
  padding: 1px 2px 3px 4px !important;
}

The padding rule isn't flipped.

[Krinkle]

This is a regression caused by 2f7f368 which stopped flipping properties with too many values (e.g. five or more consecutive values). But since !important isn't being recognised as a special value, properties with it are no longer flipped.

[mattflaschen]

I'll port the PHP fix over here.