Make RenderObject::style() return a const object

Source/core/rendering/RenderBlockFlow.cpp

Index: Source/core/rendering/RenderBlockFlow.cpp
diff --git a/Source/core/rendering/RenderBlockFlow.cpp b/Source/core/rendering/RenderBlockFlow.cpp
index 0cfbb778182253d41bc476d86130fb3c3a33ae7d..50c5420859fab8cb5a7eb5588f2a1e47ed6d4b8c 100644
--- a/Source/core/rendering/RenderBlockFlow.cpp
+++ b/Source/core/rendering/RenderBlockFlow.cpp
@@ -784,7 +784,7 @@ LayoutUnit RenderBlockFlow::adjustBlockChildForPagination(LayoutUnit logicalTopA
     return result;
 }
 
-static inline LayoutUnit calculateMinimumPageHeight(RenderStyle* renderStyle, RootInlineBox* lastLine, LayoutUnit lineTop, LayoutUnit lineBottom)
+static inline LayoutUnit calculateMinimumPageHeight(const RenderStyle* renderStyle, RootInlineBox* lastLine, LayoutUnit lineTop, LayoutUnit lineBottom)
 {
     // We may require a certain minimum number of lines per page in order to satisfy
     // orphans and widows, and that may affect the minimum page height.
@@ -1098,7 +1098,7 @@ MarginInfo::MarginInfo(RenderBlockFlow* blockFlow, LayoutUnit beforeBorderPaddin
     , m_determinedMarginBeforeQuirk(false)
     , m_discardMargin(false)
 {
-    RenderStyle* blockStyle = blockFlow->style();
+    const RenderStyle* blockStyle = blockFlow->style();
     ASSERT(blockFlow->isRenderView() || blockFlow->parent());
     m_canCollapseWithChildren = !blockFlow->createsNewFormattingContext() && !blockFlow->isRenderFlowThread() && !blockFlow->isRenderView();
 
@@ -1942,7 +1942,7 @@ void RenderBlockFlow::createFloatingObjects()
 
 void RenderBlockFlow::styleWillChange(StyleDifference diff, const RenderStyle& newStyle)
 {
-    RenderStyle* oldStyle = style();
+    const RenderStyle* oldStyle = style();
     s_canPropagateFloatIntoSibling = oldStyle ? !isFloatingOrOutOfFlowPositioned() && !avoidsFloats() : false;
     if (oldStyle && parent() && diff.needsFullLayout() && oldStyle->position() != newStyle.position()
         && containsFloats() && !isFloating() && !isOutOfFlowPositioned() && newStyle.hasOutOfFlowPosition())