Remove non-static SVGDocumentExtensions::rootElement()

This is just an alias for documentElement(), which should preferably
only be used by the SVGDocument (DOM) property.

Change-Id: I2bae17b4efd30b5be6488166d511879eaa0196b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2509577
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Auto-Submit: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822660}

third_party/blink/renderer/core/svg/graphics/svg_image.cc

@@ -56,7 +56,6 @@
 #include "third_party/blink/renderer/core/svg/animation/smil_time_container.h"
 #include "third_party/blink/renderer/core/svg/graphics/svg_image_chrome_client.h"
 #include "third_party/blink/renderer/core/svg/svg_animated_preserve_aspect_ratio.h"
-#include "third_party/blink/renderer/core/svg/svg_document_extensions.h"
 #include "third_party/blink/renderer/core/svg/svg_fe_image_element.h"
 #include "third_party/blink/renderer/core/svg/svg_image_element.h"
 #include "third_party/blink/renderer/core/svg/svg_svg_element.h"
@@ -224,8 +223,8 @@ bool SVGImage::CurrentFrameHasSingleSecurityOrigin() const {
 
   CheckLoaded();
 
-  SVGSVGElement* root_element =
-      frame->GetDocument()->AccessSVGExtensions().rootElement();
+  auto* root_element =
+      DynamicTo<SVGSVGElement>(frame->GetDocument()->documentElement());
   if (!root_element)
     return true;
 
@@ -252,7 +251,7 @@ static SVGSVGElement* SvgRootElement(Page* page) {
   if (!page)
     return nullptr;
   auto* frame = To<LocalFrame>(page->MainFrame());
-  return frame->GetDocument()->AccessSVGExtensions().rootElement();
+  return DynamicTo<SVGSVGElement>(frame->GetDocument()->documentElement());
 }
 
 LayoutSize SVGImage::ContainerSize() const {

third_party/blink/renderer/core/svg/svg_document_extensions.cc

@@ -157,11 +157,6 @@ SVGSVGElement* SVGDocumentExtensions::rootElement(const Document& document) {
   return DynamicTo<SVGSVGElement>(document.documentElement());
 }
 
-SVGSVGElement* SVGDocumentExtensions::rootElement() const {
-  DCHECK(document_);
-  return rootElement(*document_);
-}
-
 void SVGDocumentExtensions::Trace(Visitor* visitor) const {
   visitor->Trace(document_);
   visitor->Trace(time_containers_);

third_party/blink/renderer/core/svg/svg_document_extensions.h

@@ -69,7 +69,6 @@ class CORE_EXPORT SVGDocumentExtensions final
   void UpdatePan(const FloatPoint& pos) const;
 
   static SVGSVGElement* rootElement(const Document&);
-  SVGSVGElement* rootElement() const;
 
   void Trace(Visitor*) const;