--- a/layout/style/ServoStyleSheet.cpp
+++ b/layout/style/ServoStyleSheet.cpp
@@ -280,17 +280,17 @@ ServoStyleSheet::Clone(StyleSheet* aClon
   RefPtr<StyleSheet> clone = new ServoStyleSheet(*this,
     static_cast<ServoStyleSheet*>(aCloneParent),
     aCloneOwnerRule,
     aCloneDocument,
     aCloneOwningNode);
   return clone.forget();
 }
 
-CSSRuleList*
+ServoCSSRuleList*
 ServoStyleSheet::GetCssRulesInternal()
 {
   if (!mRuleList) {
     EnsureUniqueInner();
 
     RefPtr<ServoCssRules> rawRules =
       Servo_StyleSheet_GetRules(Inner()->mSheet).Consume();
     MOZ_ASSERT(rawRules);

--- a/layout/style/ServoStyleSheet.h
+++ b/layout/style/ServoStyleSheet.h
@@ -113,26 +113,29 @@ public:
     dom::CSSImportRule* aCloneOwnerRule,
     nsIDocument* aCloneDocument,
     nsINode* aCloneOwningNode) const final;
 
   // nsICSSLoaderObserver interface
   NS_IMETHOD StyleSheetLoaded(StyleSheet* aSheet, bool aWasAlternate,
                               nsresult aStatus) final;
 
+  // Internal GetCssRules method which do not have security check and
+  // completelness check.
+  ServoCSSRuleList* GetCssRulesInternal();
+
 protected:
   virtual ~ServoStyleSheet();
 
   ServoStyleSheetInner* Inner() const
   {
     return static_cast<ServoStyleSheetInner*>(mInner);
   }
 
   // Internal methods which do not have security check and completeness check.
-  dom::CSSRuleList* GetCssRulesInternal();
   uint32_t InsertRuleInternal(const nsAString& aRule,
                               uint32_t aIndex, ErrorResult& aRv);
   void DeleteRuleInternal(uint32_t aIndex, ErrorResult& aRv);
   nsresult InsertRuleIntoGroupInternal(const nsAString& aRule,
                                        css::GroupRule* aGroup,
                                        uint32_t aIndex);
 
   void EnabledStateChangedInternal() {}

--- a/layout/style/StyleSheet.cpp
+++ b/layout/style/StyleSheet.cpp
@@ -5,16 +5,17 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/StyleSheet.h"
 
 #include "mozilla/dom/CSSImportRule.h"
 #include "mozilla/dom/CSSRuleList.h"
 #include "mozilla/dom/MediaList.h"
 #include "mozilla/dom/ShadowRoot.h"
+#include "mozilla/ServoCSSRuleList.h"
 #include "mozilla/ServoStyleSheet.h"
 #include "mozilla/StyleSheetInlines.h"
 #include "mozilla/CSSStyleSheet.h"
 
 #include "mozAutoDocUpdate.h"
 #include "NullPrincipal.h"
 
 namespace mozilla {