--- a/layout/style/ServoBindingList.h
+++ b/layout/style/ServoBindingList.h
@@ -47,33 +47,29 @@ SERVO_BINDING_FUNC(Servo_StyleSheet_GetR
                    RawServoStyleSheetBorrowed sheet)
 SERVO_BINDING_FUNC(Servo_StyleSet_Init, RawServoStyleSetOwned, RawGeckoPresContextOwned pres_context)
 SERVO_BINDING_FUNC(Servo_StyleSet_RebuildData, void,
                    RawServoStyleSetBorrowed set)
 SERVO_BINDING_FUNC(Servo_StyleSet_Drop, void, RawServoStyleSetOwned set)
 SERVO_BINDING_FUNC(Servo_StyleSet_AppendStyleSheet, void,
                    RawServoStyleSetBorrowed set,
                    RawServoStyleSheetBorrowed sheet,
-                   uint32_t unique_id,
-                   bool flush)
+                   uint32_t unique_id)
 SERVO_BINDING_FUNC(Servo_StyleSet_PrependStyleSheet, void,
                    RawServoStyleSetBorrowed set,
                    RawServoStyleSheetBorrowed sheet,
-                   uint32_t unique_id,
-                   bool flush)
+                   uint32_t unique_id)
 SERVO_BINDING_FUNC(Servo_StyleSet_RemoveStyleSheet, void,
                    RawServoStyleSetBorrowed set,
-                   uint32_t unique_id,
-                   bool flush)
+                   uint32_t unique_id)
 SERVO_BINDING_FUNC(Servo_StyleSet_InsertStyleSheetBefore, void,
                    RawServoStyleSetBorrowed set,
                    RawServoStyleSheetBorrowed sheet,
                    uint32_t unique_id,
-                   uint32_t before_unique_id,
-                   bool flush)
+                   uint32_t before_unique_id)
 SERVO_BINDING_FUNC(Servo_StyleSet_FlushStyleSheets, void, RawServoStyleSetBorrowed set)
 SERVO_BINDING_FUNC(Servo_StyleSet_NoteStyleSheetsChanged, void,
                    RawServoStyleSetBorrowed set, bool author_style_disabled)
 SERVO_BINDING_FUNC(Servo_StyleSet_FillKeyframesForName, bool,
                    RawServoStyleSetBorrowed set,
                    const nsACString* property,
                    nsTimingFunctionBorrowed timing_function,
                    ServoComputedValuesBorrowed computed_values,

--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -62,18 +62,17 @@ ServoStyleSet::Init(nsPresContext* aPres
       // type, which this preserves.
 
       // Set the uniqueIDs as we go.
       entry.uniqueID = ++mUniqueIDCounter;
 
       MOZ_ASSERT(entry.sheet->RawSheet(), "We should only append non-null raw sheets.");
       Servo_StyleSet_AppendStyleSheet(mRawSet.get(),
                                       entry.sheet->RawSheet(),
-                                      entry.uniqueID,
-                                      false);
+                                      entry.uniqueID);
     }
   }
 
   // No need to Servo_StyleSet_FlushStyleSheets because we just created the
   // mRawSet, so there was nothing to flush.
 }
 
 void
@@ -167,22 +166,17 @@ ServoStyleSet::BeginUpdate()
 {
   ++mBatching;
 }
 
 nsresult
 ServoStyleSet::EndUpdate()
 {
   MOZ_ASSERT(mBatching > 0);
-  if (--mBatching > 0) {
-    return NS_OK;
-  }
-
-  Servo_StyleSet_FlushStyleSheets(mRawSet.get());
-  mStylistMayNeedRebuild = false;
+  --mBatching;
   return NS_OK;
 }
 
 already_AddRefed<nsStyleContext>
 ServoStyleSet::ResolveStyleFor(Element* aElement,
                                nsStyleContext* aParentContext,
                                LazyComputeBehavior aMayCompute)
 {
@@ -571,18 +565,17 @@ ServoStyleSet::AppendStyleSheet(SheetTyp
   // original position as part of the call to Servo_StyleSet_AppendStyleSheet.
   uint32_t oldUniqueID = RemoveSheetOfType(aType, aSheet);
   uint32_t newUniqueID = AppendSheetOfType(aType, aSheet, oldUniqueID);
 
   if (mRawSet) {
     // Maintain a mirrored list of sheets on the servo side.
     Servo_StyleSet_AppendStyleSheet(mRawSet.get(),
                                     aSheet->RawSheet(),
-                                    newUniqueID,
-                                    !mBatching);
+                                    newUniqueID);
     mStylistMayNeedRebuild = true;
   }
 
   return NS_OK;
 }
 
 nsresult
 ServoStyleSet::PrependStyleSheet(SheetType aType,
@@ -598,35 +591,34 @@ ServoStyleSet::PrependStyleSheet(SheetTy
   // original position as part of the call to Servo_StyleSet_PrependStyleSheet.
   uint32_t oldUniqueID = RemoveSheetOfType(aType, aSheet);
   uint32_t newUniqueID = PrependSheetOfType(aType, aSheet, oldUniqueID);
 
   if (mRawSet) {
     // Maintain a mirrored list of sheets on the servo side.
     Servo_StyleSet_PrependStyleSheet(mRawSet.get(),
                                      aSheet->RawSheet(),
-                                     newUniqueID,
-                                     !mBatching);
+                                     newUniqueID);
     mStylistMayNeedRebuild = true;
   }
 
   return NS_OK;
 }
 
 nsresult
 ServoStyleSet::RemoveStyleSheet(SheetType aType,
                                 ServoStyleSheet* aSheet)
 {
   MOZ_ASSERT(aSheet);
   MOZ_ASSERT(nsStyleSet::IsCSSSheetType(aType));
 
   uint32_t uniqueID = RemoveSheetOfType(aType, aSheet);
   if (mRawSet && uniqueID) {
     // Maintain a mirrored list of sheets on the servo side.
-    Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), uniqueID, !mBatching);
+    Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), uniqueID);
     mStylistMayNeedRebuild = true;
   }
 
   return NS_OK;
 }
 
 nsresult
 ServoStyleSet::ReplaceSheets(SheetType aType,
@@ -637,38 +629,32 @@ ServoStyleSet::ReplaceSheets(SheetType a
   // to express. If the need ever arises, we can easily make this more efficent,
   // probably by aligning the representations better between engines.
 
   mStylistMayNeedRebuild = true;
 
   // Remove all the existing sheets first.
   if (mRawSet) {
     for (const Entry& entry : mEntries[aType]) {
-      Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), entry.uniqueID, false);
+      Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), entry.uniqueID);
     }
   }
   mEntries[aType].Clear();
 
   // Add in all the new sheets.
   for (auto& sheet : aNewSheets) {
     uint32_t uniqueID = AppendSheetOfType(aType, sheet);
     if (mRawSet) {
       MOZ_ASSERT(sheet->RawSheet(), "Raw sheet should be in place before replacement.");
       Servo_StyleSet_AppendStyleSheet(mRawSet.get(),
                                       sheet->RawSheet(),
-                                      uniqueID,
-                                      false);
+                                      uniqueID);
     }
   }
 
-  if (!mBatching) {
-    Servo_StyleSet_FlushStyleSheets(mRawSet.get());
-    mStylistMayNeedRebuild = false;
-  }
-
   return NS_OK;
 }
 
 nsresult
 ServoStyleSet::InsertStyleSheetBefore(SheetType aType,
                                       ServoStyleSheet* aNewSheet,
                                       ServoStyleSheet* aReferenceSheet)
 {
@@ -693,18 +679,17 @@ ServoStyleSet::InsertStyleSheetBefore(Sh
                                            beforeUniqueID,
                                            oldUniqueID);
 
   if (mRawSet) {
     // Maintain a mirrored list of sheets on the servo side.
     Servo_StyleSet_InsertStyleSheetBefore(mRawSet.get(),
                                           aNewSheet->RawSheet(),
                                           newUniqueID,
-                                          beforeUniqueID,
-                                          !mBatching);
+                                          beforeUniqueID);
     mStylistMayNeedRebuild = true;
   }
 
   return NS_OK;
 }
 
 int32_t
 ServoStyleSet::SheetCount(SheetType aType) const
@@ -749,32 +734,30 @@ ServoStyleSet::AddDocStyleSheet(ServoSty
                                              beforeUniqueID,
                                              oldUniqueID);
 
     if (mRawSet) {
       // Maintain a mirrored list of sheets on the servo side.
       Servo_StyleSet_InsertStyleSheetBefore(mRawSet.get(),
                                             aSheet->RawSheet(),
                                             newUniqueID,
-                                            beforeUniqueID,
-                                            !mBatching);
+                                            beforeUniqueID);
       mStylistMayNeedRebuild = true;
     }
   } else {
     // This case is append.
     uint32_t newUniqueID = AppendSheetOfType(SheetType::Doc,
                                              aSheet,
                                              oldUniqueID);
 
     if (mRawSet) {
       // Maintain a mirrored list of sheets on the servo side.
       Servo_StyleSet_AppendStyleSheet(mRawSet.get(),
                                       aSheet->RawSheet(),
-                                      newUniqueID,
-                                      !mBatching);
+                                      newUniqueID);
       mStylistMayNeedRebuild = true;
     }
   }
 
   return NS_OK;
 }
 
 already_AddRefed<nsStyleContext>
@@ -904,20 +887,16 @@ ServoStyleSet::StyleSubtreeForReconstruc
   MOZ_ASSERT(!postTraversalRequired);
 }
 
 void
 ServoStyleSet::NoteStyleSheetsChanged()
 {
   mStylistMayNeedRebuild = true;
   Servo_StyleSet_NoteStyleSheetsChanged(mRawSet.get(), mAuthorStyleDisabled);
-  if (!mBatching) {
-    Servo_StyleSet_FlushStyleSheets(mRawSet.get());
-    mStylistMayNeedRebuild = false;
-  }
 }
 
 #ifdef DEBUG
 void
 ServoStyleSet::AssertTreeIsClean()
 {
   DocumentStyleRootIterator iter(mPresContext->Document());
   while (Element* root = iter.GetNextStyleRoot()) {