style: Don't keep two list of stylesheets in ServoStyleSet.

Just one set of stylesheets is enough. While at it, unify SheetType and Origin.

Differential Revision: https://phabricator.services.mozilla.com/D27564

components/style/gecko/conversions.rs

@@ -13,9 +13,9 @@
 use crate::gecko::values::GeckoStyleCoordConvertible;
 use crate::gecko_bindings::bindings;
 use crate::gecko_bindings::structs::{self, nsStyleCoord_CalcValue, Matrix4x4Components};
-use crate::gecko_bindings::structs::{nsStyleImage, nsresult, SheetType};
+use crate::gecko_bindings::structs::{nsStyleImage, nsresult};
 use crate::gecko_bindings::sugar::ns_style_coord::{CoordData, CoordDataMut, CoordDataValue};
-use crate::stylesheets::{Origin, RulesMutateError};
+use crate::stylesheets::RulesMutateError;
 use crate::values::computed::image::LineDirection;
 use crate::values::computed::transform::Matrix3D;
 use crate::values::computed::url::ComputedImageUrl;
@@ -818,16 +818,6 @@ impl From<RulesMutateError> for nsresult {
     }
 }
 
-impl From<Origin> for SheetType {
-    fn from(other: Origin) -> Self {
-        match other {
-            Origin::UserAgent => SheetType::Agent,
-            Origin::Author => SheetType::Doc,
-            Origin::User => SheetType::User,
-        }
-    }
-}
-
 impl TrackSize<LengthPercentage> {
     /// Return TrackSize from given two nsStyleCoord
     pub fn from_gecko_style_coords<T: CoordData>(gecko_min: &T, gecko_max: &T) -> Self {

components/style/stylesheet_set.rs

@@ -468,7 +468,14 @@ where
             .fold(0, |s, (item, _)| s + item.len())
     }
 
+    /// Returns the count of stylesheets for a given origin.
+    #[inline]
+    pub fn sheet_count(&self, origin: Origin) -> usize {
+        self.collections.borrow_for_origin(&origin).len()
+    }
+
     /// Returns the `index`th stylesheet in the set for the given origin.
+    #[inline]
     pub fn get(&self, origin: Origin, index: usize) -> Option<&S> {
         self.collections.borrow_for_origin(&origin).get(index)
     }

components/style/stylesheets/origin.rs

@@ -10,18 +10,17 @@ use std::ops::BitOrAssign;
 /// Each style rule has an origin, which determines where it enters the cascade.
 ///
 /// <https://drafts.csswg.org/css-cascade/#cascading-origins>
-#[derive(Clone, Copy, Debug, Eq, PartialEq, ToShmem)]
+#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq, ToShmem)]
 #[repr(u8)]
-#[cfg_attr(feature = "servo", derive(MallocSizeOf))]
 pub enum Origin {
     /// <https://drafts.csswg.org/css-cascade/#cascade-origin-user-agent>
-    UserAgent = 1 << 0,
+    UserAgent = 0x1,
 
     /// <https://drafts.csswg.org/css-cascade/#cascade-origin-user>
-    User = 1 << 1,
+    User = 0x2,
 
     /// <https://drafts.csswg.org/css-cascade/#cascade-origin-author>
-    Author = 1 << 2,
+    Author = 0x4,
 }
 
 impl Origin {
@@ -59,7 +58,7 @@ impl Origin {
 
 bitflags! {
     /// A set of origins. This is equivalent to Gecko's OriginFlags.
-    #[cfg_attr(feature = "servo", derive(MallocSizeOf))]
+    #[derive(MallocSizeOf)]
     pub struct OriginSet: u8 {
         /// <https://drafts.csswg.org/css-cascade/#cascade-origin-user-agent>
         const ORIGIN_USER_AGENT = Origin::UserAgent as u8;

components/style/stylist.rs

@@ -591,6 +591,18 @@ impl Stylist {
             .remove_stylesheet(Some(&self.device), sheet, guard)
     }
 
+    /// Appends a new stylesheet to the current set.
+    #[inline]
+    pub fn sheet_count(&self, origin: Origin) -> usize {
+        self.stylesheets.sheet_count(origin)
+    }
+
+    /// Appends a new stylesheet to the current set.
+    #[inline]
+    pub fn sheet_at(&self, origin: Origin, index: usize) -> Option<&StylistSheet> {
+        self.stylesheets.get(origin, index)
+    }
+
     /// Returns whether for any of the applicable style rule data a given
     /// condition is true.
     pub fn any_applicable_rule_data<E, F>(&self, element: E, mut f: F) -> bool