diff --git a/dom/webidl/CSSImportRule.webidl b/dom/webidl/CSSImportRule.webidl
index 27ad5e804329..f54faf7ce140 100644
--- a/dom/webidl/CSSImportRule.webidl
+++ b/dom/webidl/CSSImportRule.webidl
@@ -17,5 +17,5 @@ interface CSSImportRule : CSSRule {
   [SameObject, PutForwards=mediaText] readonly attribute MediaList? media;
   // Per spec, the .styleSheet is never null, but in our implementation it can
   // be.  See <https://bugzilla.mozilla.org/show_bug.cgi?id=1326509>.
-  [SameObject, BinaryName="styleSheetForBindings"] readonly attribute CSSStyleSheet? styleSheet;
+  [SameObject] readonly attribute CSSStyleSheet? styleSheet;
 };
diff --git a/layout/inspector/ServoStyleRuleMap.cpp b/layout/inspector/ServoStyleRuleMap.cpp
index 3683cecf11df..8d2ac11a6a16 100644
--- a/layout/inspector/ServoStyleRuleMap.cpp
+++ b/layout/inspector/ServoStyleRuleMap.cpp
@@ -45,12 +45,6 @@ void ServoStyleRuleMap::SheetAdded(StyleSheet& aStyleSheet) {
   }
 }
 
-void ServoStyleRuleMap::SheetCloned(StyleSheet& aStyleSheet) {
-  // Invalidate all data inside. We could probably track down all the individual
-  // rules that changed etc, but it doesn't seem worth it.
-  mTable.Clear();
-}
-
 void ServoStyleRuleMap::SheetRemoved(StyleSheet& aStyleSheet) {
   // Invalidate all data inside. This isn't strictly necessary since
   // we should always get update from document before new queries come.
diff --git a/layout/inspector/ServoStyleRuleMap.h b/layout/inspector/ServoStyleRuleMap.h
index 523f1fa6a152..7e10ef44734c 100644
--- a/layout/inspector/ServoStyleRuleMap.h
+++ b/layout/inspector/ServoStyleRuleMap.h
@@ -36,7 +36,6 @@ class ServoStyleRuleMap {
 
   void SheetAdded(StyleSheet&);
   void SheetRemoved(StyleSheet&);
-  void SheetCloned(StyleSheet&);
 
   void RuleAdded(StyleSheet& aStyleSheet, css::Rule&);
   void RuleRemoved(StyleSheet& aStyleSheet, css::Rule&);
diff --git a/layout/style/CSSCounterStyleRule.cpp b/layout/style/CSSCounterStyleRule.cpp
index 0a44146cd765..531988aa725b 100644
--- a/layout/style/CSSCounterStyleRule.cpp
+++ b/layout/style/CSSCounterStyleRule.cpp
@@ -31,11 +31,6 @@ uint16_t CSSCounterStyleRule::Type() const {
   return CSSRule_Binding::COUNTER_STYLE_RULE;
 }
 
-void CSSCounterStyleRule::SetRawAfterClone(
-    RefPtr<RawServoCounterStyleRule> aRaw) {
-  mRawRule = std::move(aRaw);
-}
-
 void CSSCounterStyleRule::GetCssText(nsACString& aCssText) const {
   Servo_CounterStyleRule_GetCssText(mRawRule, &aCssText);
 }
@@ -47,27 +42,16 @@ void CSSCounterStyleRule::GetName(nsAString& aName) {
   nsStyleUtil::AppendEscapedCSSIdent(nameStr, aName);
 }
 
-template <typename Func>
-void CSSCounterStyleRule::ModifyRule(Func aCallback) {
+void CSSCounterStyleRule::SetName(const nsAString& aName) {
   if (IsReadOnly()) {
     return;
   }
-
-  StyleSheet* sheet = GetStyleSheet();
-  if (sheet) {
-    sheet->WillDirty();
+  NS_ConvertUTF16toUTF8 name(aName);
+  if (Servo_CounterStyleRule_SetName(mRawRule, &name)) {
+    if (StyleSheet* sheet = GetStyleSheet()) {
+      sheet->RuleChanged(this, StyleRuleChangeKind::Generic);
+    }
   }
-
-  if (aCallback() && sheet) {
-    sheet->RuleChanged(this, StyleRuleChangeKind::Generic);
-  }
-}
-
-void CSSCounterStyleRule::SetName(const nsAString& aName) {
-  ModifyRule([&] {
-    NS_ConvertUTF16toUTF8 name(aName);
-    return Servo_CounterStyleRule_SetName(mRawRule, &name);
-  });
 }
 
 #define CSS_COUNTER_DESC(name_, method_)                             \
@@ -77,10 +61,15 @@ void CSSCounterStyleRule::SetName(const nsAString& aName) {
         mRawRule, eCSSCounterDesc_##method_, &aValue);               \
   }                                                                  \
   void CSSCounterStyleRule::Set##method_(const nsACString& aValue) { \
-    ModifyRule([&] {                                                 \
-      return Servo_CounterStyleRule_SetDescriptor(                   \
-          mRawRule, eCSSCounterDesc_##method_, &aValue);             \
-    });                                                              \
+    if (IsReadOnly()) {                                              \
+      return;                                                        \
+    }                                                                \
+    if (Servo_CounterStyleRule_SetDescriptor(                        \
+            mRawRule, eCSSCounterDesc_##method_, &aValue)) {         \
+      if (StyleSheet* sheet = GetStyleSheet()) {                     \
+        sheet->RuleChanged(this, StyleRuleChangeKind::Generic);      \
+      }                                                              \
+    }                                                                \
   }
 #include "nsCSSCounterDescList.h"
 #undef CSS_COUNTER_DESC
diff --git a/layout/style/CSSCounterStyleRule.h b/layout/style/CSSCounterStyleRule.h
index f546f857a7d3..4020adf5c25a 100644
--- a/layout/style/CSSCounterStyleRule.h
+++ b/layout/style/CSSCounterStyleRule.h
@@ -27,14 +27,10 @@ class CSSCounterStyleRule final : public css::Rule {
   CSSCounterStyleRule(const CSSCounterStyleRule& aCopy) = delete;
   ~CSSCounterStyleRule() = default;
 
-  template <typename Func>
-  void ModifyRule(Func);
-
  public:
   bool IsCCLeaf() const final;
 
   const RawServoCounterStyleRule* Raw() const { return mRawRule.get(); }
-  void SetRawAfterClone(RefPtr<RawServoCounterStyleRule>);
 
 #ifdef DEBUG
   void List(FILE* out = stdout, int32_t aIndent = 0) const final;
diff --git a/layout/style/CSSFontFaceRule.cpp b/layout/style/CSSFontFaceRule.cpp
index 6f6f546d316b..3287e7f54139 100644
--- a/layout/style/CSSFontFaceRule.cpp
+++ b/layout/style/CSSFontFaceRule.cpp
@@ -34,10 +34,6 @@ NS_INTERFACE_MAP_END
 NS_IMPL_ADDREF_USING_AGGREGATOR(CSSFontFaceRuleDecl, ContainingRule())
 NS_IMPL_RELEASE_USING_AGGREGATOR(CSSFontFaceRuleDecl, ContainingRule())
 
-void CSSFontFaceRuleDecl::SetRawAfterClone(RefPtr<RawServoFontFaceRule> aRaw) {
-  mRawRule = std::move(aRaw);
-}
-
 // helper for string GetPropertyValue and RemovePropertyValue
 void CSSFontFaceRuleDecl::GetPropertyValue(nsCSSFontDesc aFontDescID,
                                            nsACString& aResult) const {
@@ -201,10 +197,6 @@ uint16_t CSSFontFaceRule::Type() const {
   return CSSRule_Binding::FONT_FACE_RULE;
 }
 
-void CSSFontFaceRule::SetRawAfterClone(RefPtr<RawServoFontFaceRule> aRaw) {
-  mDecl.SetRawAfterClone(std::move(aRaw));
-}
-
 void CSSFontFaceRule::GetCssText(nsACString& aCssText) const {
   aCssText.Truncate();
   Servo_FontFaceRule_GetCssText(Raw(), &aCssText);
diff --git a/layout/style/CSSFontFaceRule.h b/layout/style/CSSFontFaceRule.h
index 0db74a949a99..d78e6bef090e 100644
--- a/layout/style/CSSFontFaceRule.h
+++ b/layout/style/CSSFontFaceRule.h
@@ -43,7 +43,6 @@ class CSSFontFaceRuleDecl final : public nsICSSDeclaration {
   inline const CSSFontFaceRule* ContainingRule() const;
 
   RefPtr<RawServoFontFaceRule> mRawRule;
-  void SetRawAfterClone(RefPtr<RawServoFontFaceRule>);
 
  private:
   void* operator new(size_t size) noexcept(true) = delete;
@@ -65,7 +64,6 @@ class CSSFontFaceRule final : public css::Rule {
   bool IsCCLeaf() const final;
 
   RawServoFontFaceRule* Raw() const { return mDecl.mRawRule; }
-  void SetRawAfterClone(RefPtr<RawServoFontFaceRule>);
 
   // WebIDL interface
   uint16_t Type() const final;
diff --git a/layout/style/CSSFontFeatureValuesRule.cpp b/layout/style/CSSFontFeatureValuesRule.cpp
index b4526e7924a3..5af4c3d444cd 100644
--- a/layout/style/CSSFontFeatureValuesRule.cpp
+++ b/layout/style/CSSFontFeatureValuesRule.cpp
@@ -28,11 +28,6 @@ void CSSFontFeatureValuesRule::List(FILE* out, int32_t aIndent) const {
 }
 #endif
 
-void CSSFontFeatureValuesRule::SetRawAfterClone(
-    RefPtr<RawServoFontFeatureValuesRule> aRaw) {
-  mRawRule = std::move(aRaw);
-}
-
 /* CSSRule implementation */
 
 void CSSFontFeatureValuesRule::GetCssText(nsACString& aCssText) const {
diff --git a/layout/style/CSSFontFeatureValuesRule.h b/layout/style/CSSFontFeatureValuesRule.h
index dec9e91bfbde..7cfe295466a8 100644
--- a/layout/style/CSSFontFeatureValuesRule.h
+++ b/layout/style/CSSFontFeatureValuesRule.h
@@ -26,7 +26,6 @@ class CSSFontFeatureValuesRule final : public css::Rule {
   virtual bool IsCCLeaf() const override;
 
   RawServoFontFeatureValuesRule* Raw() const { return mRawRule; }
-  void SetRawAfterClone(RefPtr<RawServoFontFeatureValuesRule> aRaw);
 
   // WebIDL interfaces
   uint16_t Type() const final {
diff --git a/layout/style/CSSImportRule.cpp b/layout/style/CSSImportRule.cpp
index fc13842e65a5..4e7c438942b6 100644
--- a/layout/style/CSSImportRule.cpp
+++ b/layout/style/CSSImportRule.cpp
@@ -71,28 +71,9 @@ void CSSImportRule::List(FILE* out, int32_t aIndent) const {
 }
 #endif
 
-void CSSImportRule::SetRawAfterClone(RefPtr<RawServoImportRule> aRaw) {
-  mRawRule = std::move(aRaw);
-  mChildSheet =
-      const_cast<StyleSheet*>(Servo_ImportRule_GetSheet(mRawRule.get()));
-}
-
-StyleSheet* CSSImportRule::GetStyleSheetForBindings() {
-  // FIXME(emilio): This is needed to make sure we don't expose shared sheets to
-  // the OM (see wpt /css/cssom/cssimportrule-sheet-identity.html for example).
-  //
-  // Perhaps instead we could create a clone of the stylesheet and keep it in
-  // mChildSheet, without calling EnsureUniqueInner(), or something like that?
-  if (StyleSheet* parent = GetParentStyleSheet()) {
-    parent->EnsureUniqueInner();
-  }
-  return mChildSheet;
-}
-
-dom::MediaList* CSSImportRule::GetMedia() {
-  auto* sheet = GetStyleSheetForBindings();
+dom::MediaList* CSSImportRule::GetMedia() const {
   // When Bug 1326509 is fixed, we can assert mChildSheet instead.
-  return sheet ? sheet->Media() : nullptr;
+  return mChildSheet ? mChildSheet->Media() : nullptr;
 }
 
 void CSSImportRule::DropSheetReference() {
diff --git a/layout/style/CSSImportRule.h b/layout/style/CSSImportRule.h
index 99b7483fed0d..8732b81af389 100644
--- a/layout/style/CSSImportRule.h
+++ b/layout/style/CSSImportRule.h
@@ -35,9 +35,8 @@ class CSSImportRule final : public css::Rule {
   uint16_t Type() const final { return CSSRule_Binding::IMPORT_RULE; }
   void GetCssText(nsACString& aCssText) const override;
   void GetHref(nsAString& aHref) const;
-  dom::MediaList* GetMedia();
+  dom::MediaList* GetMedia() const;
   StyleSheet* GetStyleSheet() const { return mChildSheet; }
-  StyleSheet* GetStyleSheetForBindings();
 
   // Clear the mSheet pointer on this rule and descendants.
   void DropSheetReference() final;
@@ -46,7 +45,6 @@ class CSSImportRule final : public css::Rule {
                        JS::Handle<JSObject*> aGivenProto) override;
 
   const RawServoImportRule* Raw() const { return mRawRule.get(); }
-  void SetRawAfterClone(RefPtr<RawServoImportRule>);
 
  private:
   ~CSSImportRule();
diff --git a/layout/style/CSSKeyframeRule.cpp b/layout/style/CSSKeyframeRule.cpp
index 34e450c9e649..d1a5c0b6348e 100644
--- a/layout/style/CSSKeyframeRule.cpp
+++ b/layout/style/CSSKeyframeRule.cpp
@@ -22,7 +22,6 @@ class CSSKeyframeDeclaration : public nsDOMCSSDeclaration {
   explicit CSSKeyframeDeclaration(CSSKeyframeRule* aRule) : mRule(aRule) {
     mDecls =
         new DeclarationBlock(Servo_Keyframe_GetStyle(aRule->Raw()).Consume());
-    mDecls->SetOwningRule(aRule);
   }
 
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
@@ -38,11 +37,6 @@ class CSSKeyframeDeclaration : public nsDOMCSSDeclaration {
 
   DeclarationBlock* GetOrCreateCSSDeclaration(
       Operation aOperation, DeclarationBlock** aCreated) final {
-    if (aOperation != Operation::Read && mRule) {
-      if (StyleSheet* sheet = mRule->GetStyleSheet()) {
-        sheet->WillDirty();
-      }
-    }
     return mDecls;
   }
   nsresult SetCSSDeclaration(DeclarationBlock* aDecls,
@@ -80,12 +74,6 @@ class CSSKeyframeDeclaration : public nsDOMCSSDeclaration {
     return n;
   }
 
-  void SetRawAfterClone(RawServoKeyframe* aKeyframe) {
-    mDecls->SetOwningRule(nullptr);
-    mDecls = new DeclarationBlock(Servo_Keyframe_GetStyle(aKeyframe).Consume());
-    mDecls->SetOwningRule(mRule);
-  }
-
  private:
   virtual ~CSSKeyframeDeclaration() {
     MOZ_ASSERT(!mRule, "Backpointer should have been cleared");
@@ -142,14 +130,6 @@ bool CSSKeyframeRule::IsCCLeaf() const {
   return Rule::IsCCLeaf() && !mDeclaration;
 }
 
-void CSSKeyframeRule::SetRawAfterClone(RefPtr<RawServoKeyframe> aRaw) {
-  mRaw = std::move(aRaw);
-
-  if (mDeclaration) {
-    mDeclaration->SetRawAfterClone(mRaw);
-  }
-}
-
 #ifdef DEBUG
 /* virtual */
 void CSSKeyframeRule::List(FILE* out, int32_t aIndent) const {
@@ -168,14 +148,9 @@ void CSSKeyframeRule::UpdateRule(Func aCallback) {
     return;
   }
 
-  StyleSheet* sheet = GetStyleSheet();
-  if (sheet) {
-    sheet->WillDirty();
-  }
-
   aCallback();
 
-  if (sheet) {
+  if (StyleSheet* sheet = GetStyleSheet()) {
     sheet->RuleChanged(this, StyleRuleChangeKind::Generic);
   }
 }
diff --git a/layout/style/CSSKeyframeRule.h b/layout/style/CSSKeyframeRule.h
index e97594fc6a78..2149576d8d4f 100644
--- a/layout/style/CSSKeyframeRule.h
+++ b/layout/style/CSSKeyframeRule.h
@@ -32,7 +32,6 @@ class CSSKeyframeRule final : public css::Rule {
 #endif
 
   RawServoKeyframe* Raw() const { return mRaw; }
-  void SetRawAfterClone(RefPtr<RawServoKeyframe>);
 
   // WebIDL interface
   uint16_t Type() const final { return CSSRule_Binding::KEYFRAME_RULE; }
diff --git a/layout/style/CSSKeyframesRule.cpp b/layout/style/CSSKeyframesRule.cpp
index cd6801baf4cd..5a73700d41d7 100644
--- a/layout/style/CSSKeyframesRule.cpp
+++ b/layout/style/CSSKeyframesRule.cpp
@@ -31,22 +31,6 @@ class CSSKeyframeList : public dom::CSSRuleList {
   NS_DECL_ISUPPORTS_INHERITED
   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(CSSKeyframeList, dom::CSSRuleList)
 
-  void SetRawAfterClone(RefPtr<RawServoKeyframesRule> aRaw) {
-    mRawRule = std::move(aRaw);
-    uint32_t index = 0;
-    for (css::Rule* rule : mRules) {
-      if (rule) {
-        uint32_t line = 0, column = 0;
-        RefPtr<RawServoKeyframe> keyframe =
-            Servo_KeyframesRule_GetKeyframeAt(mRawRule, index, &line, &column)
-                .Consume();
-        static_cast<CSSKeyframeRule*>(rule)->SetRawAfterClone(
-            std::move(keyframe));
-      }
-      index++;
-    }
-  }
-
   void DropSheetReference() {
     if (!mStyleSheet) {
       return;
@@ -207,13 +191,6 @@ bool CSSKeyframesRule::IsCCLeaf() const {
   return Rule::IsCCLeaf() && !mKeyframeList;
 }
 
-void CSSKeyframesRule::SetRawAfterClone(RefPtr<RawServoKeyframesRule> aRaw) {
-  mRawRule = std::move(aRaw);
-  if (mKeyframeList) {
-    mKeyframeList->SetRawAfterClone(mRawRule);
-  }
-}
-
 #ifdef DEBUG
 /* virtual */
 void CSSKeyframesRule::List(FILE* out, int32_t aIndent) const {
@@ -247,14 +224,8 @@ nsresult CSSKeyframesRule::UpdateRule(Func aCallback) {
     return NS_OK;
   }
 
-  StyleSheet* sheet = GetStyleSheet();
-  if (sheet) {
-    sheet->WillDirty();
-  }
-
   aCallback();
-
-  if (sheet) {
+  if (StyleSheet* sheet = GetStyleSheet()) {
     sheet->RuleChanged(this, StyleRuleChangeKind::Generic);
   }
 
diff --git a/layout/style/CSSKeyframesRule.h b/layout/style/CSSKeyframesRule.h
index e9b783163465..95829455545d 100644
--- a/layout/style/CSSKeyframesRule.h
+++ b/layout/style/CSSKeyframesRule.h
@@ -34,7 +34,6 @@ class CSSKeyframesRule final : public css::Rule {
   // WebIDL interface
   uint16_t Type() const final { return CSSRule_Binding::KEYFRAMES_RULE; }
   const RawServoKeyframesRule* Raw() const { return mRawRule.get(); }
-  void SetRawAfterClone(RefPtr<RawServoKeyframesRule>);
 
   void GetCssText(nsACString& aCssText) const final;
   void GetName(nsAString& aName) const;
diff --git a/layout/style/CSSMediaRule.cpp b/layout/style/CSSMediaRule.cpp
index 953677b9536f..8389663923ea 100644
--- a/layout/style/CSSMediaRule.cpp
+++ b/layout/style/CSSMediaRule.cpp
@@ -56,15 +56,6 @@ void CSSMediaRule::DropSheetReference() {
   ConditionRule::DropSheetReference();
 }
 
-void CSSMediaRule::SetRawAfterClone(RefPtr<RawServoMediaRule> aRaw) {
-  mRawRule = std::move(aRaw);
-  if (mMediaList) {
-    mMediaList->SetRawAfterClone(Servo_MediaRule_GetMedia(mRawRule).Consume());
-  }
-  css::ConditionRule::SetRawAfterClone(
-      Servo_MediaRule_GetRules(mRawRule).Consume());
-}
-
 #ifdef DEBUG
 /* virtual */
 void CSSMediaRule::List(FILE* out, int32_t aIndent) const {
diff --git a/layout/style/CSSMediaRule.h b/layout/style/CSSMediaRule.h
index 2b097d276bc9..4b21239ac1dd 100644
--- a/layout/style/CSSMediaRule.h
+++ b/layout/style/CSSMediaRule.h
@@ -28,7 +28,6 @@ class CSSMediaRule final : public css::ConditionRule {
 #endif
 
   RawServoMediaRule* Raw() const { return mRawRule; }
-  void SetRawAfterClone(RefPtr<RawServoMediaRule>);
 
   // WebIDL interface
   uint16_t Type() const override { return CSSRule_Binding::MEDIA_RULE; }
diff --git a/layout/style/CSSMozDocumentRule.cpp b/layout/style/CSSMozDocumentRule.cpp
index e31377fa3f05..145fe706ab70 100644
--- a/layout/style/CSSMozDocumentRule.cpp
+++ b/layout/style/CSSMozDocumentRule.cpp
@@ -108,13 +108,6 @@ void CSSMozDocumentRule::List(FILE* out, int32_t aIndent) const {
 }
 #endif
 
-void CSSMozDocumentRule::SetRawAfterClone(
-    RefPtr<RawServoMozDocumentRule> aRaw) {
-  mRawRule = std::move(aRaw);
-  css::ConditionRule::SetRawAfterClone(
-      Servo_MozDocumentRule_GetRules(mRawRule).Consume());
-}
-
 void CSSMozDocumentRule::GetConditionText(nsACString& aConditionText) {
   Servo_MozDocumentRule_GetConditionText(mRawRule, &aConditionText);
 }
diff --git a/layout/style/CSSMozDocumentRule.h b/layout/style/CSSMozDocumentRule.h
index a1a5f84f2186..9ae28567dbd3 100644
--- a/layout/style/CSSMozDocumentRule.h
+++ b/layout/style/CSSMozDocumentRule.h
@@ -31,7 +31,6 @@ class CSSMozDocumentRule final : public css::ConditionRule {
 #endif
 
   RawServoMozDocumentRule* Raw() const { return mRawRule; }
-  void SetRawAfterClone(RefPtr<RawServoMozDocumentRule>);
 
   // WebIDL interface
   uint16_t Type() const final { return CSSRule_Binding::DOCUMENT_RULE; }
diff --git a/layout/style/CSSNamespaceRule.cpp b/layout/style/CSSNamespaceRule.cpp
index 088db2312227..219ff5b7f51d 100644
--- a/layout/style/CSSNamespaceRule.cpp
+++ b/layout/style/CSSNamespaceRule.cpp
@@ -38,10 +38,6 @@ void CSSNamespaceRule::GetCssText(nsACString& aCssText) const {
   Servo_NamespaceRule_GetCssText(mRawRule, &aCssText);
 }
 
-void CSSNamespaceRule::SetRawAfterClone(RefPtr<RawServoNamespaceRule> aRaw) {
-  mRawRule = std::move(aRaw);
-}
-
 size_t CSSNamespaceRule::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
   return aMallocSizeOf(this);
 }
diff --git a/layout/style/CSSNamespaceRule.h b/layout/style/CSSNamespaceRule.h
index 9a29b691145a..ff28de8e7ea1 100644
--- a/layout/style/CSSNamespaceRule.h
+++ b/layout/style/CSSNamespaceRule.h
@@ -40,7 +40,6 @@ class CSSNamespaceRule final : public css::Rule {
   uint16_t Type() const final { return CSSRule_Binding::NAMESPACE_RULE; }
 
   const RawServoNamespaceRule* Raw() const { return mRawRule.get(); }
-  void SetRawAfterClone(RefPtr<RawServoNamespaceRule>);
 
   void GetNamespaceURI(nsString& aNamespaceURI) { GetURLSpec(aNamespaceURI); }
 
diff --git a/layout/style/CSSPageRule.cpp b/layout/style/CSSPageRule.cpp
index c84fd19fd24f..2fb4a943f4f2 100644
--- a/layout/style/CSSPageRule.cpp
+++ b/layout/style/CSSPageRule.cpp
@@ -17,9 +17,7 @@ namespace dom {
 
 CSSPageRuleDeclaration::CSSPageRuleDeclaration(
     already_AddRefed<RawServoDeclarationBlock> aDecls)
-    : mDecls(new DeclarationBlock(std::move(aDecls))) {
-  mDecls->SetOwningRule(Rule());
-}
+    : mDecls(new DeclarationBlock(std::move(aDecls))) {}
 
 CSSPageRuleDeclaration::~CSSPageRuleDeclaration() {
   mDecls->SetOwningRule(nullptr);
@@ -53,26 +51,18 @@ nsISupports* CSSPageRuleDeclaration::GetParentObject() const {
 
 DeclarationBlock* CSSPageRuleDeclaration::GetOrCreateCSSDeclaration(
     Operation aOperation, DeclarationBlock** aCreated) {
-  if (aOperation != Operation::Read) {
-    if (StyleSheet* sheet = Rule()->GetStyleSheet()) {
-      sheet->WillDirty();
-    }
-  }
   return mDecls;
 }
 
-void CSSPageRuleDeclaration::SetRawAfterClone(
-    RefPtr<RawServoDeclarationBlock> aDeclarationBlock) {
-  mDecls->SetOwningRule(nullptr);
-  mDecls = new DeclarationBlock(aDeclarationBlock.forget());
-  mDecls->SetOwningRule(Rule());
-}
-
 nsresult CSSPageRuleDeclaration::SetCSSDeclaration(
     DeclarationBlock* aDecl, MutationClosureData* aClosureData) {
   MOZ_ASSERT(aDecl, "must be non-null");
   CSSPageRule* rule = Rule();
 
+  if (rule->IsReadOnly()) {
+    return NS_OK;
+  }
+
   if (aDecl != mDecls) {
     mDecls->SetOwningRule(nullptr);
     RefPtr<DeclarationBlock> decls = aDecl;
@@ -139,11 +129,6 @@ bool CSSPageRule::IsCCLeaf() const {
   return !mDecls.PreservingWrapper();
 }
 
-void CSSPageRule::SetRawAfterClone(RefPtr<RawServoPageRule> aRaw) {
-  mRawRule = std::move(aRaw);
-  mDecls.SetRawAfterClone(Servo_PageRule_GetStyle(mRawRule.get()).Consume());
-}
-
 size_t CSSPageRule::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
   // TODO Implement this!
   return aMallocSizeOf(this);
diff --git a/layout/style/CSSPageRule.h b/layout/style/CSSPageRule.h
index fe20d2635ab9..59f1df667796 100644
--- a/layout/style/CSSPageRule.h
+++ b/layout/style/CSSPageRule.h
@@ -43,8 +43,6 @@ class CSSPageRuleDeclaration final : public nsDOMCSSDeclaration {
 
   explicit CSSPageRuleDeclaration(
       already_AddRefed<RawServoDeclarationBlock> aDecls);
-  void SetRawAfterClone(RefPtr<RawServoDeclarationBlock>);
-
   ~CSSPageRuleDeclaration();
 
   inline CSSPageRule* Rule();
@@ -64,7 +62,6 @@ class CSSPageRule final : public css::Rule {
   bool IsCCLeaf() const final;
 
   RawServoPageRule* Raw() const { return mRawRule; }
-  void SetRawAfterClone(RefPtr<RawServoPageRule>);
 
   // WebIDL interfaces
   uint16_t Type() const final { return CSSRule_Binding::PAGE_RULE; }
diff --git a/layout/style/CSSStyleRule.cpp b/layout/style/CSSStyleRule.cpp
index d1b01de51c6f..55da0762d64c 100644
--- a/layout/style/CSSStyleRule.cpp
+++ b/layout/style/CSSStyleRule.cpp
@@ -25,9 +25,7 @@ namespace dom {
 
 CSSStyleRuleDeclaration::CSSStyleRuleDeclaration(
     already_AddRefed<RawServoDeclarationBlock> aDecls)
-    : mDecls(new DeclarationBlock(std::move(aDecls))) {
-  mDecls->SetOwningRule(Rule());
-}
+    : mDecls(new DeclarationBlock(std::move(aDecls))) {}
 
 CSSStyleRuleDeclaration::~CSSStyleRuleDeclaration() {
   mDecls->SetOwningRule(nullptr);
@@ -61,31 +59,18 @@ nsISupports* CSSStyleRuleDeclaration::GetParentObject() const {
 
 DeclarationBlock* CSSStyleRuleDeclaration::GetOrCreateCSSDeclaration(
     Operation aOperation, DeclarationBlock** aCreated) {
-  if (aOperation != Operation::Read) {
-    if (StyleSheet* sheet = Rule()->GetStyleSheet()) {
-      sheet->WillDirty();
-    }
-  }
   return mDecls;
 }
 
-void CSSStyleRule::SetRawAfterClone(RefPtr<RawServoStyleRule> aRaw) {
-  mRawRule = std::move(aRaw);
-  mDecls.SetRawAfterClone(Servo_StyleRule_GetStyle(mRawRule).Consume());
-}
-
-void CSSStyleRuleDeclaration::SetRawAfterClone(RefPtr<RawServoDeclarationBlock> aRaw) {
-  RefPtr<DeclarationBlock> block = new DeclarationBlock(aRaw.forget());
-  mDecls->SetOwningRule(nullptr);
-  mDecls = std::move(block);
-  mDecls->SetOwningRule(Rule());
-}
-
 nsresult CSSStyleRuleDeclaration::SetCSSDeclaration(
     DeclarationBlock* aDecl, MutationClosureData* aClosureData) {
   CSSStyleRule* rule = Rule();
 
-  if (StyleSheet* sheet = rule->GetStyleSheet()) {
+  if (rule->IsReadOnly()) {
+    return NS_OK;
+  }
+
+  if (RefPtr<StyleSheet> sheet = rule->GetStyleSheet()) {
     if (aDecl != mDecls) {
       mDecls->SetOwningRule(nullptr);
       RefPtr<DeclarationBlock> decls = aDecl;
@@ -191,7 +176,10 @@ void CSSStyleRule::SetSelectorText(const nsACString& aSelectorText) {
     return;
   }
 
-  if (StyleSheet* sheet = GetStyleSheet()) {
+  if (RefPtr<StyleSheet> sheet = GetStyleSheet()) {
+    // StyleRule lives inside of the Inner, it is unsafe to call WillDirty
+    // if sheet does not already have a unique Inner.
+    sheet->AssertHasUniqueInner();
     sheet->WillDirty();
 
     // TODO(emilio): May actually be more efficient to handle this as rule
diff --git a/layout/style/CSSStyleRule.h b/layout/style/CSSStyleRule.h
index 8355091d66c1..46add412acaa 100644
--- a/layout/style/CSSStyleRule.h
+++ b/layout/style/CSSStyleRule.h
@@ -49,8 +49,6 @@ class CSSStyleRuleDeclaration final : public nsDOMCSSDeclaration {
   inline CSSStyleRule* Rule();
   inline const CSSStyleRule* Rule() const;
 
-  void SetRawAfterClone(RefPtr<RawServoDeclarationBlock>);
-
   RefPtr<DeclarationBlock> mDecls;
 };
 
@@ -83,7 +81,6 @@ class CSSStyleRule final : public BindingStyleRule, public SupportsWeakPtr {
   nsICSSDeclaration* Style() final;
 
   RawServoStyleRule* Raw() const { return mRawRule; }
-  void SetRawAfterClone(RefPtr<RawServoStyleRule>);
 
   // Methods of mozilla::css::Rule
   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const final;
diff --git a/layout/style/CSSSupportsRule.cpp b/layout/style/CSSSupportsRule.cpp
index 35c0cb5d856d..e1266c3957ab 100644
--- a/layout/style/CSSSupportsRule.cpp
+++ b/layout/style/CSSSupportsRule.cpp
@@ -59,13 +59,6 @@ void CSSSupportsRule::GetCssText(nsACString& aCssText) const {
   Servo_SupportsRule_GetCssText(mRawRule, &aCssText);
 }
 
-void CSSSupportsRule::SetRawAfterClone(RefPtr<RawServoSupportsRule> aRaw) {
-  mRawRule = std::move(aRaw);
-
-  css::ConditionRule::SetRawAfterClone(
-      Servo_SupportsRule_GetRules(mRawRule).Consume());
-}
-
 /* virtual */
 size_t CSSSupportsRule::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
   // TODO Implement this!
diff --git a/layout/style/CSSSupportsRule.h b/layout/style/CSSSupportsRule.h
index 12ac0e900703..e291f8079ca2 100644
--- a/layout/style/CSSSupportsRule.h
+++ b/layout/style/CSSSupportsRule.h
@@ -25,7 +25,6 @@ class CSSSupportsRule : public css::ConditionRule {
 #endif
 
   RawServoSupportsRule* Raw() const { return mRawRule; }
-  void SetRawAfterClone(RefPtr<RawServoSupportsRule>);
 
   // WebIDL interface
   uint16_t Type() const override { return CSSRule_Binding::SUPPORTS_RULE; }
diff --git a/layout/style/GroupRule.h b/layout/style/GroupRule.h
index cd2e574b850f..73122a79e6b6 100644
--- a/layout/style/GroupRule.h
+++ b/layout/style/GroupRule.h
@@ -55,10 +55,6 @@ class GroupRule : public Rule {
     return mRuleList->GetRule(aIndex);
   }
 
-  void SetRawAfterClone(RefPtr<ServoCssRules> aRules) {
-    mRuleList->SetRawAfterClone(std::move(aRules));
-  }
-
   /*
    * The next method should never be called unless you have first called
    * WillDirty() on the parent stylesheet.
diff --git a/layout/style/MediaList.h b/layout/style/MediaList.h
index 674d17485d5d..29ce7cfdc752 100644
--- a/layout/style/MediaList.h
+++ b/layout/style/MediaList.h
@@ -47,9 +47,6 @@ class MediaList final : public nsISupports, public nsWrapperCache {
   bool Matches(const Document&) const;
 
   void SetStyleSheet(StyleSheet* aSheet);
-  void SetRawAfterClone(RefPtr<RawServoMediaList> aRaw) {
-    mRawList = std::move(aRaw);
-  }
 
   // WebIDL
   void GetMediaText(nsACString& aMediaText);
diff --git a/layout/style/ServoCSSRuleList.cpp b/layout/style/ServoCSSRuleList.cpp
index 57a64093e6f1..131e954bfdac 100644
--- a/layout/style/ServoCSSRuleList.cpp
+++ b/layout/style/ServoCSSRuleList.cpp
@@ -49,7 +49,7 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ServoCSSRuleList)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(dom::CSSRuleList)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(ServoCSSRuleList,
                                                   dom::CSSRuleList)
-  tmp->EnumerateInstantiatedRules([&](css::Rule* aRule, uint32_t) {
+  tmp->EnumerateInstantiatedRules([&](css::Rule* aRule) {
     if (!aRule->IsCCLeaf()) {
       NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mRules[i]");
       cb.NoteXPCOMChild(aRule);
@@ -65,13 +65,12 @@ css::Rule* ServoCSSRuleList::GetRule(uint32_t aIndex) {
 #define CASE_RULE(const_, name_)                                             \
   case CSSRule_Binding::const_##_RULE: {                                     \
     uint32_t line = 0, column = 0;                                           \
-    RefPtr<RawServo##name_##Rule> raw =                                      \
+    RefPtr<RawServo##name_##Rule> rule =                                     \
         Servo_CssRules_Get##name_##RuleAt(mRawRules, aIndex, &line, &column) \
             .Consume();                                                      \
-    MOZ_ASSERT(raw);                                                         \
-    ruleObj = new CSS##name_##Rule(raw.forget(), mStyleSheet, mParentRule,   \
+    MOZ_ASSERT(rule);                                                        \
+    ruleObj = new CSS##name_##Rule(rule.forget(), mStyleSheet, mParentRule,  \
                                    line, column);                            \
-    MOZ_ASSERT(ruleObj->Type() == rule);                                     \
     break;                                                                   \
   }
       CASE_RULE(STYLE, Style)
@@ -110,12 +109,10 @@ css::Rule* ServoCSSRuleList::IndexedGetter(uint32_t aIndex, bool& aFound) {
 
 template <typename Func>
 void ServoCSSRuleList::EnumerateInstantiatedRules(Func aCallback) {
-  uint32_t index = 0;
   for (uintptr_t rule : mRules) {
     if (rule > kMaxRuleType) {
-      aCallback(CastToPtr(rule), index);
+      aCallback(CastToPtr(rule));
     }
-    index++;
   }
 }
 
@@ -149,13 +146,13 @@ void ServoCSSRuleList::DropSheetReference() {
   }
   mStyleSheet = nullptr;
   EnumerateInstantiatedRules(
-      [](css::Rule* rule, uint32_t) { rule->DropSheetReference(); });
+      [](css::Rule* rule) { rule->DropSheetReference(); });
 }
 
 void ServoCSSRuleList::DropParentRuleReference() {
   mParentRule = nullptr;
   EnumerateInstantiatedRules(
-      [](css::Rule* rule, uint32_t) { rule->DropParentRuleReference(); });
+      [](css::Rule* rule) { rule->DropParentRuleReference(); });
 }
 
 nsresult ServoCSSRuleList::InsertRule(const nsACString& aRule,
@@ -168,8 +165,6 @@ nsresult ServoCSSRuleList::InsertRule(const nsACString& aRule,
     return NS_OK;
   }
 
-  mStyleSheet->WillDirty();
-
   bool nested = !!mParentRule;
   css::Loader* loader = nullptr;
   auto allowImportRules = mStyleSheet->SelfOrAncestorIsConstructed()
@@ -219,42 +214,6 @@ uint16_t ServoCSSRuleList::GetDOMCSSRuleType(uint32_t aIndex) const {
   return CastToPtr(rule)->Type();
 }
 
-void ServoCSSRuleList::SetRawAfterClone(RefPtr<ServoCssRules> aNewRules) {
-  mRawRules = std::move(aNewRules);
-  EnumerateInstantiatedRules([&](css::Rule* aRule, uint32_t aIndex) {
-#define CASE_FOR(constant_, type_)                                           \
-  case CSSRule_Binding::constant_##_RULE: {                                  \
-    uint32_t line = 0, column = 0;                                           \
-    RefPtr<RawServo##type_##Rule> raw =                                      \
-        Servo_CssRules_Get##type_##RuleAt(mRawRules, aIndex, &line, &column) \
-            .Consume();                                                      \
-    static_cast<dom::CSS##type_##Rule*>(aRule)->SetRawAfterClone(            \
-        std::move(raw));                                                     \
-    break;                                                                   \
-  }
-    switch (aRule->Type()) {
-      CASE_FOR(STYLE, Style)
-      CASE_FOR(KEYFRAMES, Keyframes)
-      CASE_FOR(MEDIA, Media)
-      CASE_FOR(NAMESPACE, Namespace)
-      CASE_FOR(PAGE, Page)
-      CASE_FOR(SUPPORTS, Supports)
-      CASE_FOR(DOCUMENT, MozDocument)
-      CASE_FOR(IMPORT, Import)
-      CASE_FOR(FONT_FEATURE_VALUES, FontFeatureValues)
-      CASE_FOR(FONT_FACE, FontFace)
-      CASE_FOR(COUNTER_STYLE, CounterStyle)
-      case CSSRule_Binding::KEYFRAME_RULE:
-        MOZ_ASSERT_UNREACHABLE("keyframe rule cannot be here");
-        break;
-      default:
-        MOZ_ASSERT_UNREACHABLE("Which rule do we have here?");
-        break;
-    }
-#undef CASE_FOR
-  });
-}
-
 ServoCSSRuleList::~ServoCSSRuleList() {
   MOZ_ASSERT(!mStyleSheet, "Backpointer should have been cleared");
   MOZ_ASSERT(!mParentRule, "Backpointer should have been cleared");
diff --git a/layout/style/ServoCSSRuleList.h b/layout/style/ServoCSSRuleList.h
index 4db3939fbd8d..bc27b4c8b9ab 100644
--- a/layout/style/ServoCSSRuleList.h
+++ b/layout/style/ServoCSSRuleList.h
@@ -50,8 +50,6 @@ class ServoCSSRuleList final : public dom::CSSRuleList {
 
   uint16_t GetDOMCSSRuleType(uint32_t aIndex) const;
 
-  void SetRawAfterClone(RefPtr<ServoCssRules>);
-
  private:
   virtual ~ServoCSSRuleList();
 
diff --git a/layout/style/ServoStyleSet.cpp b/layout/style/ServoStyleSet.cpp
index 78489f13527b..1dbe456d76d0 100644
--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -942,13 +942,6 @@ void ServoStyleSet::RuleChanged(StyleSheet& aSheet, css::Rule* aRule,
   }
 }
 
-void ServoStyleSet::SheetCloned(StyleSheet& aSheet) {
-  mNeedsRestyleAfterEnsureUniqueInner = true;
-  if (mStyleRuleMap) {
-    mStyleRuleMap->SheetCloned(aSheet);
-  }
-}
-
 #ifdef DEBUG
 void ServoStyleSet::AssertTreeIsClean() {
   DocumentStyleRootIterator iter(mDocument);
diff --git a/layout/style/ServoStyleSet.h b/layout/style/ServoStyleSet.h
index 8f6b36be60b6..a30cee54b6fa 100644
--- a/layout/style/ServoStyleSet.h
+++ b/layout/style/ServoStyleSet.h
@@ -119,7 +119,7 @@ class ServoStyleSet {
   void RuleAdded(StyleSheet&, css::Rule&);
   void RuleRemoved(StyleSheet&, css::Rule&);
   void RuleChanged(StyleSheet&, css::Rule*, StyleRuleChangeKind);
-  void SheetCloned(StyleSheet&);
+  void SheetCloned(StyleSheet&) { mNeedsRestyleAfterEnsureUniqueInner = true; }
   void ImportRuleLoaded(dom::CSSImportRule&, StyleSheet&);
 
   // Runs style invalidation due to document state changes.
diff --git a/layout/style/StyleSheet.cpp b/layout/style/StyleSheet.cpp
index 44b2207f0eef..e1c6ec4eb65d 100644
--- a/layout/style/StyleSheet.cpp
+++ b/layout/style/StyleSheet.cpp
@@ -537,14 +537,13 @@ void StyleSheet::EnsureUniqueInner() {
 
   StyleSheetInfo* clone = mInner->CloneFor(this);
   MOZ_ASSERT(clone);
-
   mInner->RemoveSheet(this);
   mInner = clone;
 
   // Fixup the child lists and parent links in the Servo sheet. This is done
   // here instead of in StyleSheetInner::CloneFor, because it's just more
   // convenient to do so instead.
-  FixUpAfterInnerClone();
+  BuildChildListAfterInnerClone();
 
   // let our containing style sets know that if we call
   // nsPresContext::EnsureSafeToHandOutCSSRules we will need to restyle the
@@ -817,8 +816,6 @@ void StyleSheet::RuleRemoved(css::Rule& aRule) {
 }
 
 void StyleSheet::RuleChanged(css::Rule* aRule, StyleRuleChangeKind aKind) {
-  MOZ_ASSERT(!aRule || HasUniqueInner(),
-             "Shouldn't have mutated a shared sheet");
   SetModifiedRules();
   NOTIFY(RuleChanged, (*this, aRule, aKind));
 }
@@ -1109,7 +1106,7 @@ JSObject* StyleSheet::WrapObject(JSContext* aCx,
   return dom::CSSStyleSheet_Binding::Wrap(aCx, this, aGivenProto);
 }
 
-void StyleSheet::FixUpAfterInnerClone() {
+void StyleSheet::BuildChildListAfterInnerClone() {
   MOZ_ASSERT(Inner().mSheets.Length() == 1, "Should've just cloned");
   MOZ_ASSERT(Inner().mSheets[0] == this);
   MOZ_ASSERT(Inner().mChildren.IsEmpty());
@@ -1117,10 +1114,6 @@ void StyleSheet::FixUpAfterInnerClone() {
   auto* contents = Inner().mContents.get();
   RefPtr<ServoCssRules> rules = Servo_StyleSheet_GetRules(contents).Consume();
 
-  if (mRuleList) {
-    mRuleList->SetRawAfterClone(rules);
-  }
-
   uint32_t index = 0;
   while (true) {
     uint32_t line, column;  // Actually unused.
@@ -1387,6 +1380,8 @@ already_AddRefed<StyleSheet> StyleSheet::CloneAdoptedSheet(
 
 ServoCSSRuleList* StyleSheet::GetCssRulesInternal() {
   if (!mRuleList) {
+    EnsureUniqueInner();
+
     RefPtr<ServoCssRules> rawRules =
         Servo_StyleSheet_GetRules(Inner().mContents).Consume();
     MOZ_ASSERT(rawRules);
diff --git a/layout/style/StyleSheet.h b/layout/style/StyleSheet.h
index 068224ecf36e..eec11b1370ac 100644
--- a/layout/style/StyleSheet.h
+++ b/layout/style/StyleSheet.h
@@ -501,7 +501,7 @@ class StyleSheet final : public nsICSSLoaderObserver, public nsWrapperCache {
 
   // Take the recently cloned sheets from the `@import` rules, and reparent them
   // correctly to `aPrimarySheet`.
-  void FixUpAfterInnerClone();
+  void BuildChildListAfterInnerClone();
 
   void DropRuleList();