Add data about longhand properties that are affected as reset-only

[gilmoreorless]

Some shorthand properties will reset longhand properties to their initial values, but don't allow setting values for those longhands. A good example is border, which resets border-image (also a shorthand) to its initial value, but doesn't allow setting any border-image values within the border value.

These reset-only properties should be added to the data somehow.