Use C++11 features in core/html

Source/core/html/HTMLTableElement.cpp

Index: Source/core/html/HTMLTableElement.cpp
diff --git a/Source/core/html/HTMLTableElement.cpp b/Source/core/html/HTMLTableElement.cpp
index 80946123ac178e72fae4748d528f31593d3d46a2..e5d8f813d09ab0367dc8bbb8d7d50601d56d729a 100644
--- a/Source/core/html/HTMLTableElement.cpp
+++ b/Source/core/html/HTMLTableElement.cpp
@@ -403,7 +403,7 @@ static PassRefPtrWillBeRawPtr<StylePropertySet> createBorderStyle(CSSValueID val
 const StylePropertySet* HTMLTableElement::additionalPresentationAttributeStyle()
 {
     if (m_frameAttr)
-        return 0;
+        return nullptr;
 
     if (!m_borderAttr && !m_borderColorAttr) {
         // Setting the border to 'hidden' allows it to win over any border
@@ -412,7 +412,7 @@ const StylePropertySet* HTMLTableElement::additionalPresentationAttributeStyle()
             DEFINE_STATIC_REF_WILL_BE_PERSISTENT(StylePropertySet, solidBorderStyle, (createBorderStyle(CSSValueHidden)));
             return solidBorderStyle;
         }
-        return 0;
+        return nullptr;
     }
 
     if (m_borderColorAttr) {
@@ -513,7 +513,7 @@ static PassRefPtrWillBeRawPtr<StylePropertySet> createGroupBorderStyle(int rows)
 const StylePropertySet* HTMLTableElement::additionalGroupStyle(bool rows)
 {
     if (m_rulesAttr != GroupsRules)
-        return 0;
+        return nullptr;
 
     if (rows) {
         DEFINE_STATIC_REF_WILL_BE_PERSISTENT(StylePropertySet, rowBorderStyle, (createGroupBorderStyle(true)));