Make RenderObject::style() return a const object

Source/core/rendering/RenderLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 571 matching lines @@
     void updateReflectionInfo(const RenderStyle*);
 
     // FIXME: We could lazily allocate our ScrollableArea based on style properties ('overflow', ...)
     // but for now, we are always allocating it for RenderBox as it's safer.
     bool requiresScrollableArea() const { return renderBox(); }
     void updateScrollableArea();
 
     void dirtyAncestorChainVisibleDescendantStatus();
 
     bool attemptDirectCompositingUpdate(StyleDifference, const RenderStyle* oldStyle);
-    void updateTransform(const RenderStyle* oldStyle, RenderStyle* newStyle);
+    void updateTransform(const RenderStyle* oldStyle, const RenderStyle* newStyle);
 
     void dirty3DTransformedDescendantStatus();
     // Both updates the status, and returns true if descendants of this have 3d.
     bool update3DTransformedDescendantStatus();
 
     void updateOrRemoveFilterClients();
 
     void updatePaginationRecursive(bool needsPaginationUpdate = false);
     void updatePagination();
     void clearPaginationRecursive();
@@ skipping 113 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const blink::RenderLayer*);
 void showLayerTree(const blink::RenderObject*);
 #endif
 
 #endif // RenderLayer_h