function Property(prop, value, selector, priority, additionalPriority) {
  this.prop = prop;
  this.value = value;
  this.selector = selector;
  this.priority = priority || 0;
  this.additionalPriority = additionalPriority || [];
}
CSS property constructor.

@param {String} property
@param {String} value
@param {Selector} selector the property originates from
@param {Integer} priority 0 for normal properties, 2 for !important properties.
@param {Array} additional array of integers representing more detailed priorities (sorting)
@api public