Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

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 3e59ff102e5ec9226490c858d05fbb2d6bbf09a3..370877c061a43223d3f0b8c75ac9c4cf025a85d1 100644
--- a/Source/core/css/resolver/StyleResolverState.cpp
+++ b/Source/core/css/resolver/StyleResolverState.cpp
@@ -32,7 +32,7 @@ namespace WebCore {
 StyleResolverState::StyleResolverState(Document& document, Element* element, RenderStyle* parentStyle)
     : m_elementContext(element ? ElementResolveContext(*element) : ElementResolveContext())
     , m_document(document)
-    , m_style(0)
+    , m_style(nullptr)
     , m_cssToLengthConversionData(0, rootElementStyle(), document.renderView())
     , m_parentStyle(parentStyle)
     , m_applyPropertyToRegularStyle(true)
@@ -42,7 +42,7 @@ StyleResolverState::StyleResolverState(Document& document, Element* element, Ren
     , m_currentRule(0)
 {
     if (m_elementContext.resetStyleInheritance())
-        m_parentStyle = 0;
+        m_parentStyle = nullptr;
     else if (!parentStyle && m_elementContext.parentNode())
         m_parentStyle = m_elementContext.parentNode()->renderStyle();