The `transform` property supports transform functions that sometimes
need their `calc(percentage)` values to be converted to a number instead
of a length. Currently this only applies to the `scale*` family of
functions, which are marked as such in `TransformFunctions.json`.
We were not consistently applying the `NumberPercentage` type to these
functions though, and in addition, any `NumberPercentage` value would
not consider calculated values.
Initially I added this to the existing CalculationContext, but in
reality, we have some data at parse-time and different data at
resolve-time, so it made more sense to keep those separate.
Instead of needing a variety of methods for resolving a Foo, depending
on whether we have a Layout::Node available, or a percentage basis, or
a length resolution context... put those in a
CalculationResolutionContext, and just pass that one thing to these
methods. This also removes the need for separate resolve_*_percentage()
methods, because we can just pass the percentage basis in to the regular
resolve_foo() method.
This also corrects the issue that *any* calculation may need to resolve
lengths, but we previously only passed a length resolution context to
specific types in some situations. Now, they can all have one available,
though it's up to the caller to provide it.
Same again, although rotation is more complicated: `rotate`
is "equivalent to" multiple different transform function depending on
its arguments. So we can parse as one of those instead of the full
`rotate3d()`, but then need to handle this when serializing.
The only ways this varies from the `scale()` function is with parsing
and serialization. Parsing stays separate, and serialization is done by
telling `TransformationStyleValue` which property it is, and overriding
its normal `to_string()` code for properties other than `transform`.
