• Added postcss-discard-overridden to safely discard overridden rules with
  the same identifier (thanks to @Justineo).
• Added: Reduce animation/transition timing functions. Detects cubic-bezier
  functions that are equivalent to the timing keywords and compresses, as well
  as normalizing the steps timing function.
• Added the perspective-origin property to the list of supported properties
  transformed by the reduce-positions transform.