Oilpan: fix failing animation unit tests.

Source/core/animation/AnimationPlayerTest.cpp

Index: Source/core/animation/AnimationPlayerTest.cpp
diff --git a/Source/core/animation/AnimationPlayerTest.cpp b/Source/core/animation/AnimationPlayerTest.cpp
index c666a55f93a25eb91ef49b9a540286689ba2b91f..0f870d11882f194eda432c7132989b8cec408642 100644
--- a/Source/core/animation/AnimationPlayerTest.cpp
+++ b/Source/core/animation/AnimationPlayerTest.cpp
@@ -695,7 +695,7 @@ TEST_F(AnimationAnimationPlayerTest, TimeToNextEffectWhenCancelledBeforeStartRev
 
 TEST_F(AnimationAnimationPlayerTest, AttachedAnimationPlayers)
 {
-    RefPtrWillBeRawPtr<Element> element = document->createElement("foo", ASSERT_NO_EXCEPTION);
+    RefPtrWillBePersistent<Element> element = document->createElement("foo", ASSERT_NO_EXCEPTION);
 
     Timing timing;
     RefPtrWillBeRawPtr<Animation> animation = Animation::create(element.get(), nullptr, timing);
@@ -705,6 +705,7 @@ TEST_F(AnimationAnimationPlayerTest, AttachedAnimationPlayers)
     EXPECT_EQ(1, element->activeAnimations()->players().find(player.get())->value);
 
     player.release();
+    Heap::collectAllGarbage();
     EXPECT_TRUE(element->activeAnimations()->players().isEmpty());
 }