Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXSpinButton.cpp

Index: Source/modules/accessibility/AXSpinButton.cpp
diff --git a/Source/modules/accessibility/AXSpinButton.cpp b/Source/modules/accessibility/AXSpinButton.cpp
index a3d3068a25c5f26f2d50144a70c040eb64174b5f..4adf91e6b8fbff1185999424dca9b5ff72aab4ac 100644
--- a/Source/modules/accessibility/AXSpinButton.cpp
+++ b/Source/modules/accessibility/AXSpinButton.cpp
@@ -31,14 +31,14 @@
 
 namespace blink {
 
-PassRefPtr<AXSpinButton> AXSpinButton::create(AXObjectCacheImpl* axObjectCache)
+PassRefPtrWillBeRawPtr<AXSpinButton> AXSpinButton::create(AXObjectCacheImpl* axObjectCache)
 {
-    return adoptRef(new AXSpinButton(axObjectCache));
+    return adoptRefWillBeNoop(new AXSpinButton(axObjectCache));
 }
 
 AXSpinButton::AXSpinButton(AXObjectCacheImpl* axObjectCache)
     : AXMockObject(axObjectCache)
-    , m_spinButtonElement(0)
+    , m_spinButtonElement(nullptr)
 {
 }
 
@@ -46,6 +46,12 @@ AXSpinButton::~AXSpinButton()
 {
 }
 
+DEFINE_TRACE(AXSpinButton)
+{
+    AXMockObject::trace(visitor);
+    visitor->trace(m_spinButtonElement);
+}
+
 LayoutRect AXSpinButton::elementRect() const
 {
     if (!m_spinButtonElement || !m_spinButtonElement->layoutObject())
@@ -57,13 +63,13 @@ LayoutRect AXSpinButton::elementRect() const
 void AXSpinButton::detach()
 {
     AXObject::detach();
-    m_spinButtonElement = 0;
+    m_spinButtonElement = nullptr;
 }
 
 void AXSpinButton::detachFromParent()
 {
     AXObject::detachFromParent();
-    m_spinButtonElement = 0;
+    m_spinButtonElement = nullptr;
 }
 
 AccessibilityRole AXSpinButton::roleValue() const
@@ -103,9 +109,9 @@ AXSpinButtonPart::AXSpinButtonPart(AXObjectCacheImpl* axObjectCache)
 {
 }
 
-PassRefPtr<AXSpinButtonPart> AXSpinButtonPart::create(AXObjectCacheImpl* axObjectCache)
+PassRefPtrWillBeRawPtr<AXSpinButtonPart> AXSpinButtonPart::create(AXObjectCacheImpl* axObjectCache)
 {
-    return adoptRef(new AXSpinButtonPart(axObjectCache));
+    return adoptRefWillBeNoop(new AXSpinButtonPart(axObjectCache));
 }
 
 LayoutRect AXSpinButtonPart::elementRect() const