Use C++11 features in core/html

Source/core/html/HTMLOptionElement.cpp

Index: Source/core/html/HTMLOptionElement.cpp
diff --git a/Source/core/html/HTMLOptionElement.cpp b/Source/core/html/HTMLOptionElement.cpp
index 1bdde70b90d434be260de3938d7652317c9ab16a..369b1fd6ba579fae60b9c3032606aed9f4758717 100644
--- a/Source/core/html/HTMLOptionElement.cpp
+++ b/Source/core/html/HTMLOptionElement.cpp
@@ -161,7 +161,7 @@ int HTMLOptionElement::index() const
 
     int optionIndex = 0;
 
-    const WillBeHeapVector<RawPtrWillBeMember<HTMLElement> >& items = selectElement->listItems();
+    const WillBeHeapVector<RawPtrWillBeMember<HTMLElement>>& items = selectElement->listItems();
     size_t length = items.size();
     for (size_t i = 0; i < length; ++i) {
         if (!isHTMLOptionElement(*items[i]))
@@ -377,7 +377,7 @@ HTMLFormElement* HTMLOptionElement::form() const
     if (HTMLSelectElement* selectElement = ownerSelectElement())
         return selectElement->formOwner();
 
-    return 0;
+    return nullptr;
 }
 
 void HTMLOptionElement::didAddUserAgentShadowRoot(ShadowRoot& root)