Make RenderObject::style() return a const object

Source/core/rendering/style/RenderStyle.cpp

Index: Source/core/rendering/style/RenderStyle.cpp
diff --git a/Source/core/rendering/style/RenderStyle.cpp b/Source/core/rendering/style/RenderStyle.cpp
index e89db8af349ca5009b86f4ad2d9cc54e510963d5..ab20f985ce35ff44169aa007ed2e97620f2eaeb2 100644
--- a/Source/core/rendering/style/RenderStyle.cpp
+++ b/Source/core/rendering/style/RenderStyle.cpp
@@ -160,10 +160,10 @@ static StyleRecalcChange diffPseudoStyles(const RenderStyle* oldStyle, const Ren
     for (PseudoId pseudoId = FIRST_PUBLIC_PSEUDOID; pseudoId < FIRST_INTERNAL_PSEUDOID; pseudoId = static_cast<PseudoId>(pseudoId + 1)) {
         if (!oldStyle->hasPseudoStyle(pseudoId))
             continue;
-        RenderStyle* newPseudoStyle = newStyle->getCachedPseudoStyle(pseudoId);
+        const RenderStyle* newPseudoStyle = newStyle->getCachedPseudoStyle(pseudoId);
         if (!newPseudoStyle)
             return NoInherit;
-        RenderStyle* oldPseudoStyle = oldStyle->getCachedPseudoStyle(pseudoId);
+        const RenderStyle* oldPseudoStyle = oldStyle->getCachedPseudoStyle(pseudoId);
         if (oldPseudoStyle && *oldPseudoStyle != *newPseudoStyle)
             return NoInherit;
     }
@@ -329,7 +329,7 @@ void RenderStyle::removeCachedPseudoStyle(PseudoId pid)
     if (!m_cachedPseudoStyles)
         return;
     for (size_t i = 0; i < m_cachedPseudoStyles->size(); ++i) {
-        RenderStyle* pseudoStyle = m_cachedPseudoStyles->at(i).get();
+        const RenderStyle* pseudoStyle = m_cachedPseudoStyles->at(i).get();
         if (pseudoStyle->styleType() == pid) {
             m_cachedPseudoStyles->remove(i);
             return;