Make RenderObject::style() return a const object

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 1276 matching lines @@
     // they are positioned correctly. In the virtual-viewport pinch mode frame rect changes wont
     // necessarily cause a layout size change so only take this early-out if we're in old-style
     // pinch.
     if (m_frame->settings()
         && !m_frame->settings()->viewportEnabled()
         && !m_frame->settings()->pinchVirtualViewportEnabled())
         return;
 
     for (const auto& viewportConstrainedObject : *m_viewportConstrainedObjects) {
         RenderObject* renderer = viewportConstrainedObject;
-        RenderStyle* style = renderer->style();
+        const RenderStyle* style = renderer->style();
         if (widthChanged) {
             if (style->width().isFixed() && (style->left().isAuto() || style->right().isAuto()))
                 renderer->setNeedsPositionedMovementLayout();
             else
                 renderer->setNeedsLayoutAndFullPaintInvalidation();
         }
         if (heightChanged) {
             if (style->height().isFixed() && (style->top().isAuto() || style->bottom().isAuto()))
                 renderer->setNeedsPositionedMovementLayout();
             else
@@ skipping 2720 matching lines @@
         return;
 
     ScrollableArea::setScrollOrigin(origin);
 
     // Update if the scroll origin changes, since our position will be different if the content size did not change.
     if (updatePositionAtAll && updatePositionSynchronously)
         updateScrollbars(scrollOffsetDouble());
 }
 
 } // namespace blink