--- a/dom/base/CharacterData.cpp
+++ b/dom/base/CharacterData.cpp
@@ -436,17 +436,18 @@ CharacterData::ToCString(nsAString& aBuf
       }
     }
   }
 }
 #endif
 
 
 nsresult
-CharacterData::BindToTree(nsIDocument* aDocument, nsIContent* aParent,
+CharacterData::BindToTree(nsIDocument* aDocument,
+                          nsIContent* aParent,
                           nsIContent* aBindingParent,
                           bool aCompileEventHandlers)
 {
   MOZ_ASSERT(aParent || aDocument, "Must have document if no parent!");
   MOZ_ASSERT(NODE_FROM(aParent, aDocument)->OwnerDoc() == OwnerDoc(),
              "Must have the same owner document");
   MOZ_ASSERT(!aParent || aDocument == aParent->GetUncomposedDoc(),
              "aDocument must be current doc of aParent");
@@ -596,107 +597,20 @@ CharacterData::UnbindFromTree(bool aDeep
     if (aNullParent || !mParent->IsInShadowTree()) {
       slots->mContainingShadow = nullptr;
     }
   }
 
   nsNodeUtils::ParentChainChanged(this);
 }
 
-already_AddRefed<nsINodeList>
-CharacterData::GetChildren(uint32_t aFilter)
-{
-  return nullptr;
-}
-
-uint32_t
-CharacterData::GetChildCount() const
-{
-  return 0;
-}
-
-nsIContent *
-CharacterData::GetChildAt_Deprecated(uint32_t aIndex) const
-{
-  return nullptr;
-}
-
-
-int32_t
-CharacterData::ComputeIndexOf(const nsINode* aPossibleChild) const
-{
-  return -1;
-}
-
-nsresult
-CharacterData::InsertChildBefore(nsIContent* aKid,
-                                 nsIContent* aBeforeThis,
-                                 bool aNotify)
-{
-  return NS_OK;
-}
-
-void
-CharacterData::RemoveChildNode(nsIContent* aKid, bool aNotify)
-{
-}
-
-nsXBLBinding *
-CharacterData::DoGetXBLBinding() const
-{
-  return nullptr;
-}
-
-bool
-CharacterData::IsNodeOfType(uint32_t aFlags) const
-{
-  return false;
-}
-
-void
-CharacterData::SaveSubtreeState()
-{
-}
-
-#ifdef DEBUG
-void
-CharacterData::List(FILE* out, int32_t aIndent) const
-{
-}
-
-void
-CharacterData::DumpContent(FILE* out, int32_t aIndent,
-                           bool aDumpAll) const
-{
-}
-#endif
-
-bool
-CharacterData::IsLink(nsIURI** aURI) const
-{
-  *aURI = nullptr;
-  return false;
-}
-
 //----------------------------------------------------------------------
 
 // Implementation of the nsIContent interface text functions
 
-const nsTextFragment *
-CharacterData::GetText()
-{
-  return &mText;
-}
-
-uint32_t
-CharacterData::TextLength() const
-{
-  return TextDataLength();
-}
-
 nsresult
 CharacterData::SetText(const char16_t* aBuffer,
                        uint32_t aLength,
                        bool aNotify)
 {
   return SetTextInternal(0, mText.GetLength(), aBuffer, aLength, aNotify);
 }
 
@@ -754,29 +668,16 @@ CharacterData::ThreadSafeTextIsOnlyWhite
     }
 
     ++cp;
   }
 
   return true;
 }
 
-void
-CharacterData::AppendTextTo(nsAString& aResult)
-{
-  mText.AppendTo(aResult);
-}
-
-bool
-CharacterData::AppendTextTo(nsAString& aResult,
-                            const mozilla::fallible_t& aFallible)
-{
-  return mText.AppendTo(aResult, aFallible);
-}
-
 already_AddRefed<nsAtom>
 CharacterData::GetCurrentValueAtom()
 {
   nsAutoString val;
   GetData(val);
   return NS_Atomize(val);
 }
 

--- a/dom/base/CharacterData.h
+++ b/dom/base/CharacterData.h
@@ -95,96 +95,161 @@ public:
 
   NS_IMPL_FROMNODE_HELPER(CharacterData, IsCharacterData())
 
   virtual void GetNodeValueInternal(nsAString& aNodeValue) override;
   virtual void SetNodeValueInternal(const nsAString& aNodeValue,
                                     ErrorResult& aError) override;
 
   // nsINode methods
-  virtual uint32_t GetChildCount() const override;
-  virtual nsIContent *GetChildAt_Deprecated(uint32_t aIndex) const override;
-  virtual int32_t ComputeIndexOf(const nsINode* aPossibleChild) const override;
-  virtual nsresult InsertChildBefore(nsIContent* aKid, nsIContent* aBeforeThis,
-                                     bool aNotify) override;
-  virtual void RemoveChildNode(nsIContent* aKid, bool aNotify) override;
-  virtual void GetTextContentInternal(nsAString& aTextContent,
-                                      OOMReporter& aError) override
+  uint32_t GetChildCount() const final
+  {
+    return 0;
+  }
+
+  nsIContent* GetChildAt_Deprecated(uint32_t aIndex) const final
+  {
+    return nullptr;
+  }
+
+  int32_t ComputeIndexOf(const nsINode* aPossibleChild) const final
+  {
+    return -1;
+  }
+
+  nsresult InsertChildBefore(nsIContent* aKid,
+                             nsIContent* aBeforeThis,
+                             bool aNotify) final
+  {
+    return NS_OK;
+  }
+
+  void RemoveChildNode(nsIContent* aKid, bool aNotify) final
+  {
+  }
+
+  void GetTextContentInternal(nsAString& aTextContent, OOMReporter&) final
   {
     GetNodeValue(aTextContent);
   }
-  virtual void SetTextContentInternal(const nsAString& aTextContent,
-                                      nsIPrincipal* aSubjectPrincipal,
-                                      ErrorResult& aError) override
+
+  void SetTextContentInternal(const nsAString& aTextContent,
+                              nsIPrincipal* aSubjectPrincipal,
+                              ErrorResult& aError) final
   {
     // Batch possible DOMSubtreeModified events.
     mozAutoSubtreeModified subtree(OwnerDoc(), nullptr);
     return SetNodeValue(aTextContent, aError);
   }
 
   // Implementation for nsIContent
-  virtual nsresult BindToTree(nsIDocument* aDocument, nsIContent* aParent,
-                              nsIContent* aBindingParent,
-                              bool aCompileEventHandlers) override;
-  virtual void UnbindFromTree(bool aDeep = true,
-                              bool aNullParent = true) override;
+  nsresult BindToTree(nsIDocument* aDocument,
+                      nsIContent* aParent,
+                      nsIContent* aBindingParent,
+                      bool aCompileEventHandlers) override;
+
+  void UnbindFromTree(bool aDeep = true, bool aNullParent = true) override;
+
+  already_AddRefed<nsINodeList> GetChildren(uint32_t aFilter) final
+  {
+    return nullptr;
+  }
 
-  virtual already_AddRefed<nsINodeList> GetChildren(uint32_t aFilter) override;
+  const nsTextFragment* GetText() override
+  {
+    return &mText;
+  }
 
-  virtual const nsTextFragment *GetText() override;
-  virtual uint32_t TextLength() const override;
+  const nsTextFragment& TextFragment() const
+  {
+    return mText;
+  }
+
+  uint32_t TextLength() const final
+  {
+    return TextDataLength();
+  }
 
   /**
    * Set the text to the given value. If aNotify is true then
    * the document is notified of the content change.
    */
-  nsresult SetText(const char16_t* aBuffer, uint32_t aLength,
+  nsresult SetText(const char16_t* aBuffer,
+                   uint32_t aLength,
                    bool aNotify);
   /**
    * Append the given value to the current text. If aNotify is true then
    * the document is notified of the content change.
    */
   nsresult SetText(const nsAString& aStr, bool aNotify)
   {
     return SetText(aStr.BeginReading(), aStr.Length(), aNotify);
   }
 
   /**
    * Append the given value to the current text. If aNotify is true then
    * the document is notified of the content change.
    */
-  nsresult AppendText(const char16_t* aBuffer, uint32_t aLength,
+  nsresult AppendText(const char16_t* aBuffer,
+                      uint32_t aLength,
                       bool aNotify);
 
-  virtual bool TextIsOnlyWhitespace() override;
+  bool TextIsOnlyWhitespace() final;
   bool ThreadSafeTextIsOnlyWhitespace() const final;
 
   /**
    * Append the text content to aResult.
    */
-  void AppendTextTo(nsAString& aResult);
+  void AppendTextTo(nsAString& aResult) const
+  {
+    mText.AppendTo(aResult);
+  }
+
   /**
    * Append the text content to aResult.
    */
   MOZ_MUST_USE
-  bool AppendTextTo(nsAString& aResult, const fallible_t&);
+  bool AppendTextTo(nsAString& aResult, const fallible_t& aFallible) const
+  {
+    return mText.AppendTo(aResult, aFallible);
+  }
 
-  virtual void SaveSubtreeState() override;
+  void SaveSubtreeState() final
+  {
+  }
 
 #ifdef DEBUG
-  virtual void List(FILE* out, int32_t aIndent) const override;
-  virtual void DumpContent(FILE* out, int32_t aIndent, bool aDumpAll) const override;
+  void List(FILE* out, int32_t aIndent) const override
+  {
+  }
+
+  void DumpContent(FILE* out, int32_t aIndent, bool aDumpAll) const override
+  {
+  }
 #endif
 
-  virtual nsXBLBinding* DoGetXBLBinding() const override;
-  virtual bool IsNodeOfType(uint32_t aFlags) const override;
-  virtual bool IsLink(nsIURI** aURI) const override;
+  nsXBLBinding* DoGetXBLBinding() const final
+  {
+    return nullptr;
+  }
+
+  bool IsNodeOfType(uint32_t aFlags) const override
+  {
+    return false;
+  }
 
-  virtual nsresult Clone(dom::NodeInfo *aNodeInfo, nsINode **aResult,
-                         bool aPreallocateChildren) const override
+  bool IsLink(nsIURI** aURI) const final
+  {
+    *aURI = nullptr;
+    return false;
+  }
+
+  nsresult Clone(dom::NodeInfo* aNodeInfo,
+                 nsINode** aResult,
+                 bool aPreallocateChildren) const override
   {
     RefPtr<CharacterData> result = CloneDataNode(aNodeInfo, true);
     result.forget(aResult);
 
     if (!*aResult) {
       return NS_ERROR_OUT_OF_MEMORY;
     }
 
@@ -215,17 +280,17 @@ public:
 #endif
 
   NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_INHERITED(CharacterData,
                                                                    nsIContent)
 
 protected:
   virtual ~CharacterData();
 
-  virtual Element* GetNameSpaceElement() override
+  Element* GetNameSpaceElement() final
   {
     return Element::FromNodeOrNull(GetParentNode());
   }
 
   nsresult SetTextInternal(uint32_t aOffset, uint32_t aCount,
                            const char16_t* aBuffer, uint32_t aLength,
                            bool aNotify,
                            CharacterDataChangeInfo::Details* aDetails = nullptr);
@@ -234,17 +299,17 @@ protected:
    * Method to clone this node. This needs to be overriden by all derived
    * classes. If aCloneText is true the text content will be cloned too.
    *
    * @param aOwnerDocument the ownerDocument of the clone
    * @param aCloneText if true the text content will be cloned too
    * @return the clone
    */
   virtual already_AddRefed<CharacterData>
-    CloneDataNode(dom::NodeInfo *aNodeInfo, bool aCloneText) const = 0;
+    CloneDataNode(dom::NodeInfo* aNodeInfo, bool aCloneText) const = 0;
 
   nsTextFragment mText;
 
 private:
   already_AddRefed<nsAtom> GetCurrentValueAtom();
 };
 
 } // namespace dom