IntersectionObserver: second cut.

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 316ab46c290824bdda94c157bfd1b715590322bb..14fc8cc23d14d6af620cb262ef3b2e6c57b8fc83 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -54,6 +54,7 @@
 #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"
@@ -1453,8 +1454,12 @@ Node::InsertionNotificationRequest Element::insertedInto(ContainerNode* insertio
     if (!insertionPoint->isInTreeScope())
         return InsertionDone;
 
-    if (hasRareData())
-        elementRareData()->clearClassListValueForQuirksMode();
+    if (hasRareData()) {
+        ElementRareData* rareData = elementRareData();
+        rareData->clearClassListValueForQuirksMode();
+        if (rareData->intersectionObserverData())
+            rareData->intersectionObserverData()->activateValidIntersectionObservers(*this);
+    }
 
     if (isUpgradedCustomElement() && inDocument())
         CustomElement::didAttach(this, document());
@@ -1532,6 +1537,9 @@ void Element::removedFrom(ContainerNode* insertionPoint)
 
         if (ElementAnimations* elementAnimations = data->elementAnimations())
             elementAnimations->cssAnimations().cancel();
+
+        if (data->intersectionObserverData())
+            data->intersectionObserverData()->deactivateAllIntersectionObservers(*this);
     }
 }
 
@@ -2582,6 +2590,18 @@ Node* Element::insertAdjacent(const String& where, Node* newChild, ExceptionStat
     return nullptr;
 }
 
+ElementIntersectionObserverData* Element::intersectionObserverData() const
+{
+    if (elementRareData())
+        return elementRareData()->intersectionObserverData();
+    return nullptr;
+}
+
+ElementIntersectionObserverData& Element::ensureIntersectionObserverData()
+{
+    return ensureElementRareData().ensureIntersectionObserverData();
+}
+
 // Step 1 of http://domparsing.spec.whatwg.org/#insertadjacenthtml()
 static Element* contextElementForInsertion(const String& where, Element* element, ExceptionState& exceptionState)
 {