Make RenderObject::style() return a const object

Source/core/layout/LayoutSliderThumb.cpp

Index: Source/core/layout/LayoutSliderThumb.cpp
diff --git a/Source/core/layout/LayoutSliderThumb.cpp b/Source/core/layout/LayoutSliderThumb.cpp
index 04e371542cd96b860de75416e4f04ab5331c5fb2..a95069af5b9d31eb59d5f010560226f4b01c4ceb 100644
--- a/Source/core/layout/LayoutSliderThumb.cpp
+++ b/Source/core/layout/LayoutSliderThumb.cpp
@@ -45,17 +45,17 @@ LayoutSliderThumb::LayoutSliderThumb(SliderThumbElement* element)
 void LayoutSliderThumb::updateAppearance(RenderStyle* parentStyle)
 {
     if (parentStyle->appearance() == SliderVerticalPart)
-        style()->setAppearance(SliderThumbVerticalPart);
+        deprecatedMutableStyle()->setAppearance(SliderThumbVerticalPart);
     else if (parentStyle->appearance() == SliderHorizontalPart)
-        style()->setAppearance(SliderThumbHorizontalPart);
+        deprecatedMutableStyle()->setAppearance(SliderThumbHorizontalPart);
     else if (parentStyle->appearance() == MediaSliderPart)
-        style()->setAppearance(MediaSliderThumbPart);
+        deprecatedMutableStyle()->setAppearance(MediaSliderThumbPart);
     else if (parentStyle->appearance() == MediaVolumeSliderPart)
-        style()->setAppearance(MediaVolumeSliderThumbPart);
+        deprecatedMutableStyle()->setAppearance(MediaVolumeSliderThumbPart);
     else if (parentStyle->appearance() == MediaFullScreenVolumeSliderPart)
-        style()->setAppearance(MediaFullScreenVolumeSliderThumbPart);
+        deprecatedMutableStyle()->setAppearance(MediaFullScreenVolumeSliderThumbPart);
     if (style()->hasAppearance())
-        LayoutTheme::theme().adjustSliderThumbSize(style(), toElement(node()));
+        LayoutTheme::theme().adjustSliderThumbSize(deprecatedMutableStyle(), toElement(node()));
 }
 
 } // namespace blink