Make RenderObject::style() return a const object

Source/core/dom/RenderTreeBuilder.cpp

Index: Source/core/dom/RenderTreeBuilder.cpp
diff --git a/Source/core/dom/RenderTreeBuilder.cpp b/Source/core/dom/RenderTreeBuilder.cpp
index ce180e205b8abea53f2b589a082b6e8b0138de65..f4fafb9d14ca9d7f6d58917241a8913ec3c70e2b 100644
--- a/Source/core/dom/RenderTreeBuilder.cpp
+++ b/Source/core/dom/RenderTreeBuilder.cpp
@@ -149,12 +149,12 @@ void RenderTreeBuilderForElement::createRenderer()
 void RenderTreeBuilderForText::createRenderer()
 {
     LayoutObject* parentRenderer = this->parentRenderer();
-    LayoutStyle* style = parentRenderer->style();
+    LayoutStyle& style = parentRenderer->mutableStyleRef();
 
-    ASSERT(m_node->textRendererIsNeeded(*style, *parentRenderer));
+    ASSERT(m_node->textRendererIsNeeded(style, *parentRenderer));
 
     RenderText* newRenderer = m_node->createTextRenderer(style);
-    if (!parentRenderer->isChildAllowed(newRenderer, *style)) {
+    if (!parentRenderer->isChildAllowed(newRenderer, style)) {
         newRenderer->destroy();
         return;
     }
@@ -166,7 +166,7 @@ void RenderTreeBuilderForText::createRenderer()
     LayoutObject* nextRenderer = this->nextRenderer();
     m_node->setRenderer(newRenderer);
     // Parent takes care of the animations, no need to call setAnimatableStyle.
-    newRenderer->setStyle(style);
+    newRenderer->setStyle(&style);
     parentRenderer->addChild(newRenderer, nextRenderer);
 }