Revert of Oilpan: Fix weak processing for IntersectionObserver::m_root

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

Index: third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp b/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
index 1d9ec9809e2c2231d0ffc421f75a0024a7ad3529..2a9cd6f082099d2d6f1c4e72da891af2950a7052 100644
--- a/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
+++ b/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
@@ -317,22 +317,19 @@
         || m_leftMargin.type() == Percent);
 }
 
+void IntersectionObserver::rootDisappearedCallback(Visitor* visitor, void* self)
+{
+    IntersectionObserver* observer = static_cast<IntersectionObserver*>(self);
+    observer->disconnect();
+}
+
+DEFINE_TRACE(IntersectionObserver)
+{
 #if ENABLE(OILPAN)
-void IntersectionObserver::clearWeakMembers(Visitor* visitor)
-{
-    if (Heap::isHeapObjectAlive(m_root))
-        return;
-    disconnect();
-    m_root = nullptr;
-}
-#endif
-
-DEFINE_TRACE(IntersectionObserver)
-{
-#if ENABLE(OILPAN)
-    visitor->template registerWeakMembers<IntersectionObserver, &IntersectionObserver::clearWeakMembers>(this);
+    visitor->registerWeakMembers(this, m_root.get(), IntersectionObserver::rootDisappearedCallback);
 #endif
     visitor->trace(m_callback);
+    visitor->trace(m_root);
     visitor->trace(m_observations);
     visitor->trace(m_entries);
 }