This doesn't clean up as much as a whole, but it's a step in the right
direction. In particular, it allows us to start using simple bindings for:
* Filters
* Shapes and images, almost. Need to:
* Get rid of the complex -moz- gradient parsing (let
layout.css.simple-moz-gradient.enabled get to release).
* Counters, almost. Need to:
* Share the Attr representation with Gecko, by not using Option<>.
* Just another variant should be enough (ContentItem::{Attr,Prefixedattr},
maybe).
Which in turn allows us to remove a whole lot of bindings in followups to this.
The setup changes a bit. This also removes the double pointer I complained about
while reviewing the shared UA sheet patches. The old setup is:
```
SpecifiedUrl
* CssUrl
* Arc<CssUrlData>
* String
* UrlExtraData
* UrlValueSource
* Arc<CssUrlData>
* load id
* resolved uri
* CORS mode.
* ...
```
The new one removes the double reference to the url data via URLValue, and looks
like:
```
SpecifiedUrl
* CssUrl
* Arc<CssUrlData>
* String
* UrlExtraData
* CorsMode
* LoadData
* load id
* resolved URI
```
The LoadData is the only mutable bit that C++ can change, and is not used from
Rust. Ideally, in the future, we could just use rust-url to resolve the URL
after parsing or something, and make it all immutable. Maybe.
I've verified that this approach still works with the UA sheet patches (via the
LoadDataSource::Lazy).
The reordering of mWillChange is to avoid nsStyleDisplay from going over the
size limit. We want to split it up anyway in bug 1552587, but mBinding gains a
tag member, which means that we were having a bit of extra padding.
One thing I want to explore is to see if we can abuse rustc's non-zero
optimizations to predict the layout from C++, but that's something to explore at
some other point in time and with a lot of care and help from Michael (who sits
next to me and works on rustc ;)).
Differential Revision: https://phabricator.services.mozilla.com/D31742
I want to do this so that I can get rid of Either<>. The reasons for getting rid
of either are multiple:
* It doesn't generate as nice C++ code using cbindgen.
* It isn't that nice to use either from Rust.
* cbindgen has bugs with zero-sized types.
I started using this for ColorOrAuto and a few others, for now.
Differential Revision: https://phabricator.services.mozilla.com/D19844
Most of types just derive it using proc_macro directly. Some of value
types need manual impl.
In my current plan, this new trait will be used in bug 1434130 to expose
values as well.
Bug: 1455576
Reviewed-by: emilio
MozReview-Commit-ID: LI7fy45VkRw
This should fix the following two "expected to fail" tests:
- getComputedStyle(elem) for url() listStyleImage uses the resolved URL
and elem.style uses the original URL
- getComputedStyle(elem) for url() listStyle uses the resolved URL
and elem.style uses the original URL
