--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -5482,59 +5482,59 @@ nsDocument::UnblockDOMContentLoaded()
                         &nsDocument::DispatchContentLoadedEvents);
     Dispatch(TaskCategory::Other, ev.forget());
   } else {
     DispatchContentLoadedEvents();
   }
 }
 
 void
-nsDocument::ContentStateChanged(nsIContent* aContent, EventStates aStateMask)
+nsIDocument::ContentStateChanged(nsIContent* aContent, EventStates aStateMask)
 {
   NS_PRECONDITION(!nsContentUtils::IsSafeToRunScript(),
                   "Someone forgot a scriptblocker");
   NS_DOCUMENT_NOTIFY_OBSERVERS(ContentStateChanged,
                                (this, aContent, aStateMask));
 }
 
 void
-nsDocument::DocumentStatesChanged(EventStates aStateMask)
+nsIDocument::DocumentStatesChanged(EventStates aStateMask)
 {
   UpdateDocumentStates(aStateMask);
   NS_DOCUMENT_NOTIFY_OBSERVERS(DocumentStatesChanged, (this, aStateMask));
 }
 
 void
-nsDocument::StyleRuleChanged(StyleSheet* aSheet, css::Rule* aStyleRule)
+nsIDocument::StyleRuleChanged(StyleSheet* aSheet, css::Rule* aStyleRule)
 {
   if (!StyleSheetChangeEventsEnabled()) {
     return;
   }
 
   DO_STYLESHEET_NOTIFICATION(StyleRuleChangeEvent,
                              "StyleRuleChanged",
                              mRule,
                              aStyleRule);
 }
 
 void
-nsDocument::StyleRuleAdded(StyleSheet* aSheet, css::Rule* aStyleRule)
+nsIDocument::StyleRuleAdded(StyleSheet* aSheet, css::Rule* aStyleRule)
 {
   if (!StyleSheetChangeEventsEnabled()) {
     return;
   }
 
   DO_STYLESHEET_NOTIFICATION(StyleRuleChangeEvent,
                              "StyleRuleAdded",
                              mRule,
                              aStyleRule);
 }
 
 void
-nsDocument::StyleRuleRemoved(StyleSheet* aSheet, css::Rule* aStyleRule)
+nsIDocument::StyleRuleRemoved(StyleSheet* aSheet, css::Rule* aStyleRule)
 {
   if (!StyleSheetChangeEventsEnabled()) {
     return;
   }
 
   DO_STYLESHEET_NOTIFICATION(StyleRuleChangeEvent,
                              "StyleRuleRemoved",
                              mRule,

--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -494,29 +494,16 @@ public:
   // observers.
   virtual void BeginUpdate(nsUpdateType aUpdateType) override;
   virtual void EndUpdate(nsUpdateType aUpdateType) override;
   virtual void BeginLoad() override;
   virtual void EndLoad() override;
 
   virtual void SetReadyStateInternal(ReadyState rs) override;
 
-  virtual void ContentStateChanged(nsIContent* aContent,
-                                   mozilla::EventStates aStateMask)
-                                     override;
-  virtual void DocumentStatesChanged(
-                 mozilla::EventStates aStateMask) override;
-
-  virtual void StyleRuleChanged(mozilla::StyleSheet* aStyleSheet,
-                                mozilla::css::Rule* aStyleRule) override;
-  virtual void StyleRuleAdded(mozilla::StyleSheet* aStyleSheet,
-                              mozilla::css::Rule* aStyleRule) override;
-  virtual void StyleRuleRemoved(mozilla::StyleSheet* aStyleSheet,
-                                mozilla::css::Rule* aStyleRule) override;
-
   virtual void FlushPendingNotifications(mozilla::FlushType aType) final override;
   virtual void FlushExternalResources(mozilla::FlushType aType) override;
   virtual void SetXMLDeclaration(const char16_t *aVersion,
                                  const char16_t *aEncoding,
                                  const int32_t aStandalone) override;
   virtual void GetXMLDeclaration(nsAString& aVersion,
                                  nsAString& aEncoding,
                                  nsAString& Standalone) override;

--- a/dom/base/nsIDocument.h
+++ b/dom/base/nsIDocument.h
@@ -1689,32 +1689,32 @@ public:
   virtual void SetReadyStateInternal(ReadyState rs) = 0;
   ReadyState GetReadyStateEnum()
   {
     return mReadyState;
   }
 
   // notify that a content node changed state.  This must happen under
   // a scriptblocker but NOT within a begin/end update.
-  virtual void ContentStateChanged(nsIContent* aContent,
-                                   mozilla::EventStates aStateMask) = 0;
+  void ContentStateChanged(
+      nsIContent* aContent, mozilla::EventStates aStateMask);
 
   // Notify that a document state has changed.
   // This should only be called by callers whose state is also reflected in the
   // implementation of nsDocument::GetDocumentState.
-  virtual void DocumentStatesChanged(mozilla::EventStates aStateMask) = 0;
+  void DocumentStatesChanged(mozilla::EventStates aStateMask);
 
   // Observation hooks for style data to propagate notifications
   // to document observers
-  virtual void StyleRuleChanged(mozilla::StyleSheet* aStyleSheet,
-                                mozilla::css::Rule* aStyleRule) = 0;
-  virtual void StyleRuleAdded(mozilla::StyleSheet* aStyleSheet,
-                              mozilla::css::Rule* aStyleRule) = 0;
-  virtual void StyleRuleRemoved(mozilla::StyleSheet* aStyleSheet,
-                                mozilla::css::Rule* aStyleRule) = 0;
+  void StyleRuleChanged(mozilla::StyleSheet* aStyleSheet,
+                        mozilla::css::Rule* aStyleRule);
+  void StyleRuleAdded(mozilla::StyleSheet* aStyleSheet,
+                      mozilla::css::Rule* aStyleRule);
+  void StyleRuleRemoved(mozilla::StyleSheet* aStyleSheet,
+                        mozilla::css::Rule* aStyleRule);
 
   /**
    * Flush notifications for this document and its parent documents
    * (since those may affect the layout of this one).
    */
   virtual void FlushPendingNotifications(mozilla::FlushType aType) = 0;
 
   /**