Make RenderObject::style() return a const object

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 94112877fa204de1f52ac4d9106c7a3aa6c1c58e..2a7ef7fcc264cdf00493396b7cfa78e80a401f59 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -333,7 +333,7 @@ void RenderLayer::updateTransformationMatrix()
     }
 }
 
-void RenderLayer::updateTransform(const RenderStyle* oldStyle, RenderStyle* newStyle)
+void RenderLayer::updateTransform(const RenderStyle* oldStyle, const RenderStyle* newStyle)
 {
     if (oldStyle && newStyle->transformDataEquivalent(*oldStyle))
         return;
@@ -893,7 +893,7 @@ TransformationMatrix RenderLayer::perspectiveTransform() const
     if (!renderer()->hasTransformRelatedProperty())
         return TransformationMatrix();
 
-    RenderStyle* style = renderer()->style();
+    const RenderStyle* style = renderer()->style();
     if (!style->hasPerspective())
         return TransformationMatrix();
 
@@ -924,7 +924,7 @@ FloatPoint RenderLayer::perspectiveOrigin() const
         return FloatPoint();
 
     const LayoutRect borderBox = toRenderBox(renderer())->borderBoxRect();
-    RenderStyle* style = renderer()->style();
+    const RenderStyle* style = renderer()->style();
 
     return FloatPoint(floatValueForLength(style->perspectiveOriginX(), borderBox.width().toFloat()), floatValueForLength(style->perspectiveOriginY(), borderBox.height().toFloat()));
 }