Oilpan: Prepare to move AXObjectCache to the heap

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index d263b1c6ff1c222c7dacf2e0fda6eb41a186a023..0ac6882b846f53beeaa2edb0ae97df00e92133fd 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -1005,15 +1005,19 @@ IntRect Element::screenRect() const
 const AtomicString& Element::computedRole()
 {
     document().updateLayoutIgnorePendingStylesheets();
-    OwnPtr<ScopedAXObjectCache> cache = ScopedAXObjectCache::create(document());
-    return cache->get()->computedRoleForNode(this);
+    OwnPtrWillBeRawPtr<ScopedAXObjectCache> cache = ScopedAXObjectCache::create(document());
+    const AtomicString& role = cache->get()->computedRoleForNode(this);
+    cache->dispose();
+    return role;
 }
 
 String Element::computedName()
 {
     document().updateLayoutIgnorePendingStylesheets();
-    OwnPtr<ScopedAXObjectCache> cache = ScopedAXObjectCache::create(document());
-    return cache->get()->computedNameForNode(this);
+    OwnPtrWillBeRawPtr<ScopedAXObjectCache> cache = ScopedAXObjectCache::create(document());
+    String name = cache->get()->computedNameForNode(this);
+    cache->dispose();
+    return name;
 }
 
 const AtomicString& Element::getAttribute(const AtomicString& localName) const