Oilpan: fix failing animation unit tests.

Source/core/animation/AnimationTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/animation/Animation.h"
 
 #include "bindings/v8/Dictionary.h"
 #include "core/animation/AnimationClock.h"
 #include "core/animation/AnimationHelpers.h"
@@ skipping 441 matching lines @@
 {
     // This test expects incorrect behaviour should be removed once Element
     // and Animation are moved to Oilpan. See crbug.com/362404 for context.
     Timing timing;
     timing.iterationDuration = 5;
     RefPtrWillBeRawPtr<Animation> animation = Animation::create(element.get(), nullptr, timing);
     EXPECT_EQ(element.get(), animation->target());
     document->timeline().play(animation.get());
     document.clear();
     element.clear();
-    Heap::collectAllGarbage();
+#if !ENABLE(OILPAN)
     EXPECT_EQ(0, animation->target());
+#endif
 }
 
 } // namespace WebCore