Oilpan: Replace RefPtrs to Document in core/{accessibility,animation,fetch} with Oilpan transition …

Source/core/animation/AnimationStackTest.cpp

Index: Source/core/animation/AnimationStackTest.cpp
diff --git a/Source/core/animation/AnimationStackTest.cpp b/Source/core/animation/AnimationStackTest.cpp
index 23c0ce59341f3c0ccce5087027167a61ea14996c..5ebdf835d6fdf97fda73aa47b30dcaebeb3c9f01 100644
--- a/Source/core/animation/AnimationStackTest.cpp
+++ b/Source/core/animation/AnimationStackTest.cpp
@@ -76,7 +76,7 @@ protected:
         return toLegacyStyleInterpolation(interpolation)->currentValue().get();
     }
 
-    RefPtr<Document> document;
+    RefPtrWillBePersistent<Document> document;
     RefPtrWillBePersistent<AnimationTimeline> timeline;
     RefPtrWillBePersistent<Element> element;
 };