IntersectionObserver: use nullptr for implicit root.

third_party/WebKit/Source/core/dom/Element.cpp

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index 7c286936357b055b17ba342c2581c8daf2be69cc..c92dcffd103bec5754e55a7dd01a4182b848899b 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -57,6 +57,7 @@
 #include "core/dom/ClientRectList.h"
 #include "core/dom/DatasetDOMStringMap.h"
 #include "core/dom/ElementDataCache.h"
+#include "core/dom/ElementIntersectionObserverData.h"
 #include "core/dom/ElementRareData.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/ExceptionCode.h"
@@ -67,7 +68,6 @@
 #include "core/dom/MutationRecord.h"
 #include "core/dom/NamedNodeMap.h"
 #include "core/dom/NodeComputedStyle.h"
-#include "core/dom/NodeIntersectionObserverData.h"
 #include "core/dom/PresentationAttributeStyle.h"
 #include "core/dom/PseudoElement.h"
 #include "core/dom/ScriptableDocumentParser.h"
@@ -2876,13 +2876,13 @@ Node* Element::insertAdjacent(const String& where,
   return nullptr;
 }
 
-NodeIntersectionObserverData* Element::intersectionObserverData() const {
+ElementIntersectionObserverData* Element::intersectionObserverData() const {
   if (hasRareData())
     return elementRareData()->intersectionObserverData();
   return nullptr;
 }
 
-NodeIntersectionObserverData& Element::ensureIntersectionObserverData() {
+ElementIntersectionObserverData& Element::ensureIntersectionObserverData() {
   return ensureElementRareData().ensureIntersectionObserverData();
 }