Extend Servo's @page parsing to match Gecko's CSS 2.2 behavior, where only
margin properties are allowed in an @page rule. Other properties are ignored.
MozReview-Commit-ID: IPYUlnkLYSb
animation_type takes following values:
animation_type="none" for non-animatable properties
animation_type="normal" for animatable properties
animation_type="discrete" for animatable but discrete type of animations
We use string value to distinguish the case where no animation_type is
specified.
animation_type="discrete" will be used in a subsequent patch to make a property
animatable as discrete type.
While we're here we also:
* remove any code conditional on style_struct.gecko_ffi_name, since all
style structs now do have a corresponding Geckos struct
* add new UIReset and XUL style structs, so that all Gecko structs are
now present (apart from Variables, which is special)
This is a new attempt of #10586, after Simon Sapin's great cleanups in #10749 has landed. I have adjusted the changes to the new structure that was introduced, and also only done a few of the longhand ones. Will certainly continue on this as soon as we have a basic agreement that this style is reasonable.
