style: Make Servo_StyleSet_NoteStyleSheetsChanged take a set of origins to dirty.

components/style/gecko_bindings/sugar/mod.rs

@@ -13,6 +13,7 @@ mod ns_style_auto_array;
 pub mod ns_style_coord;
 mod ns_t_array;
 mod ns_timing_function;
+mod origin_flags;
 pub mod ownership;
 pub mod refptr;
 mod style_complex_color;

components/style/gecko_bindings/sugar/origin_flags.rs

@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Helper to iterate over `OriginFlags` bits.
+
+use gecko_bindings::structs::OriginFlags;
+use gecko_bindings::structs::OriginFlags_Author;
+use gecko_bindings::structs::OriginFlags_User;
+use gecko_bindings::structs::OriginFlags_UserAgent;
+use stylesheets::Origin;
+
+impl OriginFlags {
+    /// Returns an iterator over the origins present in the `OriginFlags`,
+    /// in order from highest priority (author) to lower (user agent).
+    pub fn iter(self) -> OriginFlagsIter {
+        OriginFlagsIter {
+            origin_flags: self,
+            cur: 0,
+        }
+    }
+}
+
+/// Iterates over the origins present in an `OriginFlags`, in order from
+/// highest priority (author) to lower (user agent).
+pub struct OriginFlagsIter {
+    origin_flags: OriginFlags,
+    cur: usize,
+}
+
+impl Iterator for OriginFlagsIter {
+    type Item = Origin;
+
+    fn next(&mut self) -> Option<Origin> {
+        loop {
+            let (bit, origin) = match self.cur {
+                0 => (OriginFlags_Author, Origin::Author),
+                1 => (OriginFlags_User, Origin::User),
+                2 => (OriginFlags_UserAgent, Origin::UserAgent),
+                _ => return None,
+            };
+
+            self.cur += 1;
+
+            if (self.origin_flags & bit).0 != 0 {
+                return Some(origin);
+            }
+        }
+    }
+}