--- a/servo/ports/geckolib/glue.rs
+++ b/servo/ports/geckolib/glue.rs
@@ -113,16 +113,17 @@ use style::sequential;
 use style::shared_lock::{SharedRwLockReadGuard, StylesheetGuards, ToCssWithGuard, Locked};
 use style::string_cache::Atom;
 use style::style_adjuster::StyleAdjuster;
 use style::stylesheets::{CssRule, CssRules, CssRuleType, CssRulesHelpers, DocumentRule};
 use style::stylesheets::{FontFeatureValuesRule, ImportRule, KeyframesRule, MallocSizeOfWithGuard};
 use style::stylesheets::{MallocSizeOfWithRepeats, MediaRule};
 use style::stylesheets::{NamespaceRule, Origin, PageRule, SizeOfState, StyleRule, SupportsRule};
 use style::stylesheets::StylesheetContents;
+use style::stylesheets::StylesheetInDocument;
 use style::stylesheets::StylesheetLoader as StyleStylesheetLoader;
 use style::stylesheets::keyframes_rule::{Keyframe, KeyframeSelector, KeyframesStepValue};
 use style::stylesheets::supports_rule::parse_condition_or_declaration;
 use style::stylist::RuleInclusion;
 use style::thread_state;
 use style::timer::Timer;
 use style::traversal::{DomTraversal, TraversalDriver};
 use style::traversal::resolve_style;
@@ -844,22 +845,20 @@ pub extern "C" fn Servo_StyleSheet_FromU
 pub extern "C" fn Servo_StyleSet_AppendStyleSheet(
     raw_data: RawServoStyleSetBorrowed,
     sheet: *const ServoStyleSheet,
 ) {
     let global_style_data = &*GLOBAL_STYLE_DATA;
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let mut data = &mut *data;
     let guard = global_style_data.shared_lock.read();
-    data.stylesheets.append_stylesheet(
-        &data.stylist,
-        unsafe { GeckoStyleSheet::new(sheet) },
-        &guard
-    );
-    data.clear_stylist();
+    let sheet = unsafe { GeckoStyleSheet::new(sheet) };
+    let origin = sheet.contents(&guard).origin;
+    data.stylesheets.append_stylesheet(&data.stylist, sheet, &guard);
+    data.clear_stylist_origin(&origin);
 }
 
 #[no_mangle]
 pub extern "C" fn Servo_StyleSet_MediumFeaturesChanged(
     raw_data: RawServoStyleSetBorrowed,
     viewport_units_used: *mut bool,
 ) -> bool {
     let global_style_data = &*GLOBAL_STYLE_DATA;
@@ -893,58 +892,56 @@ pub extern "C" fn Servo_StyleSet_MediumF
 pub extern "C" fn Servo_StyleSet_PrependStyleSheet(
     raw_data: RawServoStyleSetBorrowed,
     sheet: *const ServoStyleSheet,
 ) {
     let global_style_data = &*GLOBAL_STYLE_DATA;
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let mut data = &mut *data;
     let guard = global_style_data.shared_lock.read();
-    data.stylesheets.prepend_stylesheet(
-        &data.stylist,
-        unsafe { GeckoStyleSheet::new(sheet) },
-        &guard,
-    );
-    data.clear_stylist();
+    let sheet = unsafe { GeckoStyleSheet::new(sheet) };
+    let origin = sheet.contents(&guard).origin;
+    data.stylesheets.prepend_stylesheet(&data.stylist, sheet, &guard);
+    data.clear_stylist_origin(&origin);
 }
 
 #[no_mangle]
 pub extern "C" fn Servo_StyleSet_InsertStyleSheetBefore(
     raw_data: RawServoStyleSetBorrowed,
     sheet: *const ServoStyleSheet,
     before_sheet: *const ServoStyleSheet
 ) {
     let global_style_data = &*GLOBAL_STYLE_DATA;
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let mut data = &mut *data;
     let guard = global_style_data.shared_lock.read();
+    let sheet = unsafe { GeckoStyleSheet::new(sheet) };
+    let origin = sheet.contents(&guard).origin;
     data.stylesheets.insert_stylesheet_before(
         &data.stylist,
-        unsafe { GeckoStyleSheet::new(sheet) },
+        sheet,
         unsafe { GeckoStyleSheet::new(before_sheet) },
         &guard,
     );
-    data.clear_stylist();
+    data.clear_stylist_origin(&origin);
 }
 
 #[no_mangle]
 pub extern "C" fn Servo_StyleSet_RemoveStyleSheet(
     raw_data: RawServoStyleSetBorrowed,
     sheet: *const ServoStyleSheet
 ) {
     let global_style_data = &*GLOBAL_STYLE_DATA;
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let mut data = &mut *data;
     let guard = global_style_data.shared_lock.read();
-    data.stylesheets.remove_stylesheet(
-        &data.stylist,
-        unsafe { GeckoStyleSheet::new(sheet) },
-        &guard,
-    );
-    data.clear_stylist();
+    let sheet = unsafe { GeckoStyleSheet::new(sheet) };
+    let origin = sheet.contents(&guard).origin;
+    data.stylesheets.remove_stylesheet(&data.stylist, sheet, &guard);
+    data.clear_stylist_origin(&origin);
 }
 
 #[no_mangle]
 pub extern "C" fn Servo_StyleSet_FlushStyleSheets(
     raw_data: RawServoStyleSetBorrowed,
     doc_element: RawGeckoElementBorrowedOrNull,
 ) {
     let global_style_data = &*GLOBAL_STYLE_DATA;