Both _gtk_css_style_property_print_value() and
_gtk_css_style_property_compute_value() aren't necessary anymore and are
replaced by _gtk_css_value_print() and _gtk_css_value_comptue()
respectively.
Equality tests are done with _gtk_css_value_equal(). There is no need to
do it per-property, equal values will still be equal.
This essentially reverts 24f5d54329e028347bd76af42e86ed190c1229a2 and
92c7a7171e1240b6d961ee5b6f9ab6b596e98904.
Also, in places where we're computing a new CssValue based on an
old one, make sure that if nothing changes we're returning a reference
to the old one, rather than creating a new identical instance.
Instead of on-demand resolvage, we now resolve during lookup. The step
is done via
_gtk_css_style_property_compute_value()
which currently calls into
_gtk_css_style_compute_value()
That function has all the old resolving machinery.
The only part missing for now is the handling of win32 code. It will be
added back later.
We can't print shorthands, so don't try.
In particular, I want to get away from shorthands being representable
using GValue, and this function kinda requires that.
