Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXImageMapLink.cpp

Index: Source/modules/accessibility/AXImageMapLink.cpp
diff --git a/Source/modules/accessibility/AXImageMapLink.cpp b/Source/modules/accessibility/AXImageMapLink.cpp
index 1d26401d4755a2eb79ab61d194e7432ed4608edc..d9f7e6163237b3ef356f0a1add4b3b1ffc9bfc63 100644
--- a/Source/modules/accessibility/AXImageMapLink.cpp
+++ b/Source/modules/accessibility/AXImageMapLink.cpp
@@ -54,9 +54,9 @@ void AXImageMapLink::detachFromParent()
     m_mapElement = nullptr;
 }
 
-PassRefPtr<AXImageMapLink> AXImageMapLink::create(AXObjectCacheImpl& axObjectCache)
+PassRefPtrWillBeRawPtr<AXImageMapLink> AXImageMapLink::create(AXObjectCacheImpl& axObjectCache)
 {
-    return adoptRef(new AXImageMapLink(axObjectCache));
+    return adoptRefWillBeNoop(new AXImageMapLink(axObjectCache));
 }
 
 AXObject* AXImageMapLink::computeParent() const
@@ -141,4 +141,11 @@ LayoutRect AXImageMapLink::elementRect() const
     return m_areaElement->computeRect(layoutObject);
 }
 
+DEFINE_TRACE(AXImageMapLink)
+{
+    visitor->trace(m_areaElement);
+    visitor->trace(m_mapElement);
+    AXMockObject::trace(visitor);
+}
+
 } // namespace blink