Make RenderObject::style() return a const object

Source/core/layout/LayoutSliderContainer.cpp

Index: Source/core/layout/LayoutSliderContainer.cpp
diff --git a/Source/core/layout/LayoutSliderContainer.cpp b/Source/core/layout/LayoutSliderContainer.cpp
index a53c3dffa13f69e153e4aec9408f3818b1e83f0c..6a8d0aa8309e19649227c4b399eb5c3b7cd17f55 100644
--- a/Source/core/layout/LayoutSliderContainer.cpp
+++ b/Source/core/layout/LayoutSliderContainer.cpp
@@ -58,7 +58,7 @@ inline static Decimal sliderPosition(HTMLInputElement* element)
 inline static bool hasVerticalAppearance(HTMLInputElement* input)
 {
     ASSERT(input->renderer());
-    RenderStyle* sliderStyle = input->renderer()->style();
+    const RenderStyle* sliderStyle = input->renderer()->style();
 
     return sliderStyle->appearance() == SliderVerticalPart;
 }
@@ -100,13 +100,13 @@ void LayoutSliderContainer::layout()
 {
     HTMLInputElement* input = toHTMLInputElement(node()->shadowHost());
     bool isVertical = hasVerticalAppearance(input);
-    style()->setFlexDirection(isVertical ? FlowColumn : FlowRow);
+    deprecatedMutableStyle()->setFlexDirection(isVertical ? FlowColumn : FlowRow);
     TextDirection oldTextDirection = style()->direction();
     if (isVertical) {
         // FIXME: Work around rounding issues in RTL vertical sliders. We want them to
         // render identically to LTR vertical sliders. We can remove this work around when
         // subpixel rendering is enabled on all ports.
-        style()->setDirection(LTR);
+        deprecatedMutableStyle()->setDirection(LTR);
     }
 
     Element* thumbElement = input->userAgentShadowRoot()->getElementById(ShadowElementNames::sliderThumb());
@@ -122,7 +122,7 @@ void LayoutSliderContainer::layout()
 
     RenderFlexibleBox::layout();
 
-    style()->setDirection(oldTextDirection);
+    deprecatedMutableStyle()->setDirection(oldTextDirection);
     // These should always exist, unless someone mutates the shadow DOM (e.g., in the inspector).
     if (!thumb || !track)
         return;