Oilpan: Prepare moving ShadowRoot to oilpan.

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 d0ecdf815c4a6f5086d6ea5c7f8d38e187946b7a..945fd931fdff96ae0057e666dde1c20433273258 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -1738,7 +1738,7 @@ CustomElementDefinition* Element::customElementDefinition() const
     return 0;
 }
 
-PassRefPtr<ShadowRoot> Element::createShadowRoot(ExceptionState& exceptionState)
+PassRefPtrWillBeRawPtr<ShadowRoot> Element::createShadowRoot(ExceptionState& exceptionState)
 {
     if (alwaysCreateUserAgentShadowRoot())
         ensureUserAgentShadowRoot();
@@ -1751,7 +1751,7 @@ PassRefPtr<ShadowRoot> Element::createShadowRoot(ExceptionState& exceptionState)
         return nullptr;
     }
 
-    return PassRefPtr<ShadowRoot>(ensureShadow().addShadowRoot(*this, ShadowRoot::AuthorShadowRoot));
+    return PassRefPtrWillBeRawPtr<ShadowRoot>(ensureShadow().addShadowRoot(*this, ShadowRoot::AuthorShadowRoot));
 }
 
 ShadowRoot* Element::shadowRoot() const