Bug 1444580: Devirtualize GetImplementation. r=smaug

MozReview-Commit-ID: 2nsR595RotH

dom/base/nsDocument.cpp

@@ -5660,7 +5660,7 @@ nsIDocument::GetDoctype() const
 }
 
 DOMImplementation*
-nsDocument::GetImplementation(ErrorResult& rv)
+nsIDocument::GetImplementation(ErrorResult& rv)
 {
   if (!mDOMImplementation) {
     nsCOMPtr<nsIURI> uri;

dom/base/nsDocument.h

@@ -713,9 +713,6 @@ public:
   virtual nsIDOMNode* AsDOMNode() override { return this; }
 
   // WebIDL bits
-  virtual mozilla::dom::DOMImplementation*
-    GetImplementation(mozilla::ErrorResult& rv) override;
-
   virtual already_AddRefed<Element> CreateElement(const nsAString& aTagName,
                                                   const mozilla::dom::ElementCreationOptionsOrString& aOptions,
                                                   ErrorResult& rv) override;
@@ -890,8 +887,6 @@ private:
   // Set if we've found a URL for the current picture
   nsString mPreloadPictureFoundSource;
 
-  RefPtr<mozilla::dom::DOMImplementation> mDOMImplementation;
-
   RefPtr<nsContentList> mImageMaps;
 
   nsCString mScrollToRef;

dom/base/nsIDocument.h

@@ -2910,8 +2910,7 @@ public:
   static already_AddRefed<nsIDocument>
     Constructor(const GlobalObject& aGlobal,
                 mozilla::ErrorResult& rv);
-  virtual mozilla::dom::DOMImplementation*
-    GetImplementation(mozilla::ErrorResult& rv) = 0;
+  mozilla::dom::DOMImplementation* GetImplementation(mozilla::ErrorResult& rv);
   MOZ_MUST_USE nsresult GetURL(nsString& retval) const;
   MOZ_MUST_USE nsresult GetDocumentURI(nsString& retval) const;
   // Return the URI for the document.
@@ -4052,6 +4051,8 @@ protected:
   // non-null when this document is in fullscreen mode.
   nsWeakPtr mFullscreenRoot;
 
+  RefPtr<mozilla::dom::DOMImplementation> mDOMImplementation;
+
   nsTArray<RefPtr<mozilla::StyleSheet>> mOnDemandBuiltInUASheets;
   nsTArray<RefPtr<mozilla::StyleSheet>> mAdditionalSheets[AdditionalSheetTypeCount];