Make RenderObject::style() return a const object

Source/core/css/resolver/StyleResolverState.cpp

Index: Source/core/css/resolver/StyleResolverState.cpp
diff --git a/Source/core/css/resolver/StyleResolverState.cpp b/Source/core/css/resolver/StyleResolverState.cpp
index 1ec955272b13c23d8dc65661f253f882a85390b5..5d90f5b9bfa8831816b038b72a0ec9f71b1b9087 100644
--- a/Source/core/css/resolver/StyleResolverState.cpp
+++ b/Source/core/css/resolver/StyleResolverState.cpp
@@ -29,7 +29,7 @@
 
 namespace blink {
 
-StyleResolverState::StyleResolverState(Document& document, const ElementResolveContext& elementContext, LayoutStyle* parentStyle)
+StyleResolverState::StyleResolverState(Document& document, const ElementResolveContext& elementContext, const LayoutStyle* parentStyle)
     : m_elementContext(elementContext)
     , m_document(document)
     , m_style(nullptr)
@@ -45,7 +45,7 @@ StyleResolverState::StyleResolverState(Document& document, const ElementResolveC
     m_elementStyleResources.setDeviceScaleFactor(document.frameHost()->deviceScaleFactor());
 }
 
-StyleResolverState::StyleResolverState(Document& document, Element* element, LayoutStyle* parentStyle)
+StyleResolverState::StyleResolverState(Document& document, Element* element, const LayoutStyle* parentStyle)
     : StyleResolverState(document, element ? ElementResolveContext(*element) : ElementResolveContext(document), parentStyle)
 {
 }