Use refs for non-null GraphicsContext, Scrollbar, etc. in scrollbar related code

third_party/WebKit/Source/core/testing/Internals.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 2499 matching lines @@
 {
     LayoutObject* layoutObject = node->layoutObject();
     if (!layoutObject)
         return false;
     PaintLayer* layer = layoutObject->enclosingLayer();
     if (!layer)
         return false;
     ScrollableArea* scrollableArea = layer->scrollableArea();
     if (!scrollableArea)
         return false;
-    ScrollAnimatorBase* animator = layer->scrollableArea()->scrollAnimator();
-    if (!animator)
-        return false;
-
-    return animator->setScrollbarsVisibleForTesting(visible);
+    return layer->scrollableArea()->scrollAnimator().setScrollbarsVisibleForTesting(visible);
 }
 
 void Internals::forceRestrictIFramePermissions()
 {
     RuntimeEnabledFeatures::setRestrictIFramePermissionsEnabled(true);
 }
 
 double Internals::monotonicTimeToZeroBasedDocumentTime(double platformTime, ExceptionState& exceptionState)
 {
     Document* document = contextDocument();
@@ skipping 13 matching lines @@
     mediaElement->setNetworkState(static_cast<WebMediaPlayer::NetworkState>(state));
 }
 
 // TODO(liberato): remove once autoplay gesture override experiment concludes.
 void Internals::triggerAutoplayViewportCheck(HTMLMediaElement* element)
 {
     element->triggerAutoplayViewportCheckForTesting();
 }
 
 } // namespace blink