Oilpan: Mark SVGElement::InvalidationGuard and SVGElement::InstanceUpdateBlocker STACK_ALLOCATED().

and makes their element members Member<>.

BUG=357163

Review URL: https://codereview.chromium.org/334223009

git-svn-id: svn://svn.chromium.org/blink/trunk@176271 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/svg/SVGElement.h

@@ -160,22 +160,25 @@ public:
     bool inUseShadowTree() const;
 
     class InvalidationGuard {
+        STACK_ALLOCATED();
         WTF_MAKE_NONCOPYABLE(InvalidationGuard);
     public:
         InvalidationGuard(SVGElement* element) : m_element(element) { }
         ~InvalidationGuard() { m_element->invalidateInstances(); }
+
     private:
-        SVGElement* m_element;
+        RawPtrWillBeMember<SVGElement> m_element;
     };
 
     class InstanceUpdateBlocker {
+        STACK_ALLOCATED();
         WTF_MAKE_NONCOPYABLE(InstanceUpdateBlocker);
     public:
         InstanceUpdateBlocker(SVGElement* targetElement);
         ~InstanceUpdateBlocker();
 
     private:
-        SVGElement* m_targetElement;
+        RawPtrWillBeMember<SVGElement> m_targetElement;
     };
 
     void invalidateInstances();