Make RenderObject::style() return a const object

Source/core/editing/VisibleUnits.cpp

Index: Source/core/editing/VisibleUnits.cpp
diff --git a/Source/core/editing/VisibleUnits.cpp b/Source/core/editing/VisibleUnits.cpp
index 94a694b8a86267f1556fa858d3b498be31c9fce5..f6102515e5241b88584c2c86ce3d7457f9818758 100644
--- a/Source/core/editing/VisibleUnits.cpp
+++ b/Source/core/editing/VisibleUnits.cpp
@@ -1115,7 +1115,7 @@ VisiblePosition startOfParagraph(const VisiblePosition& c, EditingBoundaryCrossi
             n = NodeTraversal::previousPostOrder(*n, startBlock);
             continue;
         }
-        RenderStyle* style = r->style();
+        const RenderStyle* style = r->style();
         if (style->visibility() != VISIBLE) {
             n = NodeTraversal::previousPostOrder(*n, startBlock);
             continue;
@@ -1194,7 +1194,7 @@ VisiblePosition endOfParagraph(const VisiblePosition &c, EditingBoundaryCrossing
             n = NodeTraversal::next(*n, stayInsideBlock);
             continue;
         }
-        RenderStyle* style = r->style();
+        const RenderStyle* style = r->style();
         if (style->visibility() != VISIBLE) {
             n = NodeTraversal::next(*n, stayInsideBlock);
             continue;