diff --git a/layout/style/CSSStyleSheet.cpp b/layout/style/CSSStyleSheet.cpp
index f811405590d8..6c79946753c9 100644
--- a/layout/style/CSSStyleSheet.cpp
+++ b/layout/style/CSSStyleSheet.cpp
@@ -568,16 +568,6 @@ CSSStyleSheet::GetStyleRuleAt(int32_t aIndex) const
   return Inner()->mOrderedRules.SafeObjectAt(aIndex);
 }
 
-void
-CSSStyleSheet::AppendAllChildSheets(nsTArray<CSSStyleSheet*>& aArray)
-{
-  for (StyleSheet* child = GetFirstChild(); child;
-       child = child->mNext) {
-
-    aArray.AppendElement(child->AsGecko());
-  }
-}
-
 already_AddRefed<StyleSheet>
 CSSStyleSheet::Clone(StyleSheet* aCloneParent,
                      css::ImportRule* aCloneOwnerRule,
diff --git a/layout/style/CSSStyleSheet.h b/layout/style/CSSStyleSheet.h
index cce2b86f70d8..4259862787cf 100644
--- a/layout/style/CSSStyleSheet.h
+++ b/layout/style/CSSStyleSheet.h
@@ -140,9 +140,6 @@ public:
   NS_IMETHOD StyleSheetLoaded(StyleSheet* aSheet, bool aWasAlternate,
                               nsresult aStatus) override;
 
-  // Append all of this sheet's child sheets to aArray.
-  void AppendAllChildSheets(nsTArray<CSSStyleSheet*>& aArray);
-
   bool UseForPresentation(nsPresContext* aPresContext,
                             nsMediaQueryResultCacheKey& aKey) const;
 
diff --git a/layout/style/ServoStyleSet.cpp b/layout/style/ServoStyleSet.cpp
index 6265152150e8..a1abcc3d8503 100644
--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -987,9 +987,29 @@ ServoStyleSet::ComputeAnimationValue(
 bool
 ServoStyleSet::EnsureUniqueInnerOnCSSSheets()
 {
+  AutoTArray<StyleSheet*, 32> queue;
+  for (auto& entryArray : mSheets) {
+    for (auto& sheet : entryArray) {
+      queue.AppendElement(sheet);
+    }
+  }
   // This is a stub until more of the functionality of nsStyleSet is
   // replicated for Servo here.
 
+  // Bug 1290276 will replicate the nsStyleSet work of checking
+  // a nsBindingManager
+
+  while (!queue.IsEmpty()) {
+    uint32_t idx = queue.Length() - 1;
+    StyleSheet* sheet = queue[idx];
+    queue.RemoveElementAt(idx);
+
+    sheet->EnsureUniqueInner();
+
+    // Enqueue all the sheet's children.
+    sheet->AppendAllChildSheets(queue);
+  }
+
   bool res = mNeedsRestyleAfterEnsureUniqueInner;
   mNeedsRestyleAfterEnsureUniqueInner = false;
   return res;
diff --git a/layout/style/StyleSheet.cpp b/layout/style/StyleSheet.cpp
index db86f5a2ee38..a2b338c0b3a1 100644
--- a/layout/style/StyleSheet.cpp
+++ b/layout/style/StyleSheet.cpp
@@ -458,6 +458,14 @@ StyleSheet::EnsureUniqueInner()
   }
 }
 
+void
+StyleSheet::AppendAllChildSheets(nsTArray<StyleSheet*>& aArray)
+{
+  for (StyleSheet* child = GetFirstChild(); child; child = child->mNext) {
+    aArray.AppendElement(child);
+  }
+}
+
 // WebIDL CSSStyleSheet API
 
 #define FORWARD_INTERNAL(method_, args_) \
diff --git a/layout/style/StyleSheet.h b/layout/style/StyleSheet.h
index 4d8199e8eee2..eaa7e65ffb1b 100644
--- a/layout/style/StyleSheet.h
+++ b/layout/style/StyleSheet.h
@@ -124,6 +124,9 @@ public:
 
   void EnsureUniqueInner();
 
+  // Append all of this sheet's child sheets to aArray.
+  void AppendAllChildSheets(nsTArray<StyleSheet*>& aArray);
+
   // style sheet owner info
   enum DocumentAssociationMode {
     // OwnedByDocument means mDocument owns us (possibly via a chain of other
diff --git a/layout/style/nsStyleSet.cpp b/layout/style/nsStyleSet.cpp
index c1a7d9a2baa5..a6f2e390c685 100644
--- a/layout/style/nsStyleSet.cpp
+++ b/layout/style/nsStyleSet.cpp
@@ -2638,9 +2638,9 @@ nsStyleSet::MediumFeaturesChanged()
 bool
 nsStyleSet::EnsureUniqueInnerOnCSSSheets()
 {
-  AutoTArray<CSSStyleSheet*, 32> queue;
+  AutoTArray<StyleSheet*, 32> queue;
   for (SheetType type : gCSSSheetTypes) {
-    for (CSSStyleSheet* sheet : mSheets[type]) {
+    for (StyleSheet* sheet : mSheets[type]) {
       queue.AppendElement(sheet);
     }
   }
@@ -2660,7 +2660,7 @@ nsStyleSet::EnsureUniqueInnerOnCSSSheets()
 
   while (!queue.IsEmpty()) {
     uint32_t idx = queue.Length() - 1;
-    CSSStyleSheet* sheet = queue[idx];
+    StyleSheet* sheet = queue[idx];
     queue.RemoveElementAt(idx);
 
     sheet->EnsureUniqueInner();