style: Update cbindgen.

This cleans up the pattern of "Use a private dtor so that the helper functions
do the right thing" by enabling it everywhere using:

  mozilla/cbindgen#377

It also caught some uninitialized value issues.

I think they're mostly harmless since we zero-initialize our structs:

https://searchfox.org/mozilla-central/rev/325c1a707819602feff736f129cb36055ba6d94f/servo/components/style/properties/gecko.mako.rs#632

And since we override the clip rect, which is the other bit of code that was
failing to build with this change.

Differential Revision: https://phabricator.services.mozilla.com/D43491

components/style/values/computed/text.rs

@@ -198,8 +198,6 @@ impl TextDecorationsInEffect {
 }
 
 /// Computed value for the text-emphasis-style property
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(Clone, Debug, MallocSizeOf, PartialEq, ToCss, ToResolvedValue)]
 #[allow(missing_docs)]
 #[repr(C, u8)]

components/style/values/generics/effects.rs

@@ -34,8 +34,6 @@ pub struct GenericBoxShadow<Color, SizeLength, BlurShapeLength, ShapeLength> {
 pub use self::GenericBoxShadow as BoxShadow;
 
 /// A generic value for a single `filter`.
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 #[animation(no_bound(U))]
 #[derive(

components/style/values/generics/grid.rs

@@ -185,8 +185,6 @@ impl Parse for GridLine<specified::Integer> {
 /// avoid re-implementing it for the computed type.
 ///
 /// <https://drafts.csswg.org/css-grid/#typedef-track-breadth>
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Animate,
     Clone,
@@ -230,8 +228,6 @@ impl<L> TrackBreadth<L> {
 /// generic only to avoid code bloat. It only takes `<length-percentage>`
 ///
 /// <https://drafts.csswg.org/css-grid/#typedef-track-size>
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Clone,
     Debug,
@@ -494,8 +490,6 @@ impl<L: ToCss, I: ToCss> ToCss for TrackRepeat<L, I> {
 }
 
 /// Track list values. Can be <track-size> or <track-repeat>
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Animate,
     Clone,
@@ -729,8 +723,6 @@ impl ToCss for LineNameList {
 }
 
 /// Variants for `<grid-template-rows> | <grid-template-columns>`
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Animate,
     Clone,

components/style/values/generics/svg.rs

@@ -9,7 +9,6 @@ use cssparser::Parser;
 use style_traits::ParseError;
 
 /// The fallback of an SVG paint server value.
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Animate,
     Clone,
@@ -43,8 +42,6 @@ pub use self::GenericSVGPaintFallback as SVGPaintFallback;
 /// An SVG paint value
 ///
 /// <https://www.w3.org/TR/SVG2/painting.html#SpecifyingPaint>
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[animation(no_bound(Url))]
 #[derive(
     Animate,
@@ -84,8 +81,6 @@ impl<C, U> Default for SVGPaint<C, U> {
 ///
 /// Whereas the spec only allows PaintServer to have a fallback, Gecko lets the
 /// context properties have a fallback as well.
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[animation(no_bound(U))]
 #[derive(
     Animate,

components/style/values/generics/transform.rs

@@ -151,7 +151,6 @@ fn is_same<N: PartialEq>(x: &N, y: &N) -> bool {
 )]
 #[repr(C, u8)]
 /// A single operation in the list of a `transform` value
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 pub enum GenericTransformOperation<Angle, Number, Length, Integer, LengthPercentage>
 where
     Angle: Zero,

components/style/values/generics/url.rs

@@ -5,8 +5,6 @@
 //! Generic types for url properties.
 
 /// An image url or none, used for example in list-style-image
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Animate,
     Clone,

components/style/values/specified/font.rs

@@ -1091,8 +1091,6 @@ bitflags! {
 )]
 #[repr(C, u8)]
 /// Set of variant alternates
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 pub enum VariantAlternates {
     /// Enables display of stylistic alternates
     #[css(function)]

components/style/values/specified/list.rs

@@ -126,8 +126,6 @@ pub struct QuoteList(
 
 /// Specified and computed `quotes` property: `auto`, `none`, or a list
 /// of characters.
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Clone,
     Debug,

components/style/values/specified/motion.rs

@@ -15,7 +15,6 @@ use style_traits::{ParseError, StyleParseErrorKind};
 /// The offset-path value.
 ///
 /// https://drafts.fxtf.org/motion-1/#offset-path-property
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(
     Animate,
     Clone,

components/style/values/specified/position.rs

@@ -707,8 +707,6 @@ fn is_name_code_point(c: char) -> bool {
 /// The syntax of this property also provides a visualization of the structure
 /// of the grid, making the overall layout of the grid container easier to
 /// understand.
-///
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[repr(C, u8)]
 #[derive(
     Clone,

components/style/values/specified/text.rs

@@ -132,7 +132,6 @@ impl ToComputedValue for LineHeight {
 }
 
 /// A generic value for the `text-overflow` property.
-/// cbindgen:derive-tagged-enum-copy-constructor=true
 #[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
 #[repr(C, u8)]
 pub enum TextOverflowSide {