style: Use an AutoTArray for atom arrays in attributes (class / part).

These are never empty, and storing 4 elements inline seems worth it
given we also heap-allocate the array itself.

Depends on D100592

Differential Revision: https://phabricator.services.mozilla.com/D100593

1 files changed, 6 insertions, 3 deletions

diff --git a/components/style/gecko/snapshot_helpers.rs b/components/style/gecko/snapshot_helpers.rs
index f34fca40f1c..8d99f84a958 100644
--- a/components/style/gecko/snapshot_helpers.rs
+++ b/components/style/gecko/snapshot_helpers.rs
@@ -43,14 +43,16 @@ unsafe fn get_class_or_part_from_attr(attr: &structs::nsAttrValue) -> Class {
             (*container).mType,
             structs::nsAttrValue_ValueType_eAtomArray
         );
-        let array = (*container)
+        // NOTE: Bindgen doesn't deal with AutoTArray, so cast it below.
+        let array: *mut u8 = *(*container)
             .__bindgen_anon_1
             .mValue
             .as_ref()
             .__bindgen_anon_1
             .mAtomArray
             .as_ref();
-        return Class::More(&***array)
+        let array = array as *const structs::nsTArray<structs::RefPtr<nsAtom>>;
+        return Class::More(&**array)
     }
     debug_assert_eq!(base_type, structs::nsAttrValue_ValueBaseType_eStringBase);
     Class::None
@@ -132,7 +134,8 @@ pub fn has_class_or_part(
         Class::One(atom) => unsafe { case_sensitivity.eq_atom(name, WeakAtom::new(atom)) },
         Class::More(atoms) => match case_sensitivity {
             CaseSensitivity::CaseSensitive => {
-                atoms.iter().any(|atom| atom.mRawPtr == name.as_ptr())
+                let name_ptr = name.as_ptr();
+                atoms.iter().any(|atom| atom.mRawPtr == name_ptr)
             },
             CaseSensitivity::AsciiCaseInsensitive => unsafe {
                 atoms