Oilpan: Prepare to move form control ua shadow elements to Oilpan heap.

Source/core/html/shadow/SliderThumbElement.h

Index: Source/core/html/shadow/SliderThumbElement.h
diff --git a/Source/core/html/shadow/SliderThumbElement.h b/Source/core/html/shadow/SliderThumbElement.h
index 255d58a0e1dd49ed921e6c29ca6726918dc95559..ce5d536d33d3fbc252ebd89ff34b21ce1f67fd11 100644
--- a/Source/core/html/shadow/SliderThumbElement.h
+++ b/Source/core/html/shadow/SliderThumbElement.h
@@ -46,7 +46,7 @@ class FloatPoint;
 
 class SliderThumbElement FINAL : public HTMLDivElement {
 public:
-    static PassRefPtr<SliderThumbElement> create(Document&);
+    static PassRefPtrWillBeRawPtr<SliderThumbElement> create(Document&);
 
     void setPositionFromValue();
 
@@ -96,7 +96,7 @@ private:
 
 class SliderContainerElement FINAL : public HTMLDivElement {
 public:
-    static PassRefPtr<SliderContainerElement> create(Document&);
+    static PassRefPtrWillBeRawPtr<SliderContainerElement> create(Document&);
 
 private:
     SliderContainerElement(Document&);