Move the Widget hierarchy to the Oilpan heap.

Source/platform/scroll/ScrollAnimatorNone.cpp

Index: Source/platform/scroll/ScrollAnimatorNone.cpp
diff --git a/Source/platform/scroll/ScrollAnimatorNone.cpp b/Source/platform/scroll/ScrollAnimatorNone.cpp
index d018d53809e6ae85a33f00309267d1aa0795f4d3..0592df03665a97e2df68982f24e65bd895b9532d 100644
--- a/Source/platform/scroll/ScrollAnimatorNone.cpp
+++ b/Source/platform/scroll/ScrollAnimatorNone.cpp
@@ -35,7 +35,7 @@
 #include <algorithm>
 #include "platform/scroll/ScrollableArea.h"
 #include "wtf/CurrentTime.h"
-#include "wtf/PassOwnPtr.h"
+#include "wtf/PassRefPtr.h"
 
 #include "platform/TraceEvent.h"
 
@@ -45,11 +45,11 @@ const double kFrameRate = 60;
 const double kTickTime = 1 / kFrameRate;
 const double kMinimumTimerInterval = .001;
 
-PassOwnPtr<ScrollAnimator> ScrollAnimator::create(ScrollableArea* scrollableArea)
+PassRefPtr<ScrollAnimator> ScrollAnimator::create(ScrollableArea* scrollableArea)
 {
     if (scrollableArea && scrollableArea->scrollAnimatorEnabled())
-        return adoptPtr(new ScrollAnimatorNone(scrollableArea));
-    return adoptPtr(new ScrollAnimator(scrollableArea));
+        return adoptRef(new ScrollAnimatorNone(scrollableArea));
+    return adoptRef(new ScrollAnimator(scrollableArea));
 }
 
 ScrollAnimatorNone::Parameters::Parameters()