Disable transform optimizations

[RobinMalfait]

This PR disables transform optimizations for now because they are causing issues for CSS transitions and @keyframes. This is because currently minification only minifies if the result is actually shorter.

There are situations where this is not the case:

@keyframes rain {
  0% {transform: translateY(0vh) rotate(0deg);}
  100% {transform: translateY(120vh) rotate(360deg);}
}

Gets optimized to:

 @keyframes rain {
  0% {transform: matrix(1, 0, 0, 1, 0, 0);}
  100% {transform: translateY(120vh) rotate(360deg);}
}

The issue is that this means that the transform property is no longer animatable because different steps in the keyframes have different properties.

I didn't just drop the code, but commented it out with a TODO to the linked issue so that it's easier to re-enable it later.

Fixes: #288