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 1279 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) {
         LayoutObject* renderer = viewportConstrainedObject;
-        LayoutStyle* style = renderer->style();
+        const LayoutStyle& style = renderer->styleRef();
         if (widthChanged) {
-            if (style->width().isFixed() && (style->left().isAuto() || style->right().isAuto()))
+            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()))
+            if (style.height().isFixed() && (style.top().isAuto() || style.bottom().isAuto()))
                 renderer->setNeedsPositionedMovementLayout();
             else
                 renderer->setNeedsLayoutAndFullPaintInvalidation();
         }
     }
 }
 
 IntSize FrameView::scrollOffsetForViewportConstrainedObjects() const
 {
     return roundedIntSize(viewportConstrainedVisibleContentRect().location());
@@ skipping 2735 matching lines @@
 {
     Settings* settings = frame().settings();
     if (!settings || !settings->rootLayerScrolls())
         return this;
 
     RenderView* renderView = this->renderView();
     return renderView ? renderView->scrollableArea() : nullptr;
 }
 
 } // namespace blink