Use nullptr instead of 0 in xml and xmlhttprequest.

Source/core/xml/XPathResult.cpp

Index: Source/core/xml/XPathResult.cpp
diff --git a/Source/core/xml/XPathResult.cpp b/Source/core/xml/XPathResult.cpp
index 613a3ed2b76f0df1d93d9a8279768608a91d425b..ad6a5cf3e80349cd8bd6a0a51f6d1af7e2c59869 100644
--- a/Source/core/xml/XPathResult.cpp
+++ b/Source/core/xml/XPathResult.cpp
@@ -155,7 +155,7 @@ Node* XPathResult::singleNodeValue(ExceptionState& exceptionState) const
 {
     if (resultType() != ANY_UNORDERED_NODE_TYPE && resultType() != FIRST_ORDERED_NODE_TYPE) {
         exceptionState.throwTypeError("The result type is not a single node.");
-        return 0;
+        return nullptr;
     }
 
     const NodeSet& nodes = m_value.toNodeSet(0);
@@ -187,16 +187,16 @@ Node* XPathResult::iterateNext(ExceptionState& exceptionState)
 {
     if (resultType() != UNORDERED_NODE_ITERATOR_TYPE && resultType() != ORDERED_NODE_ITERATOR_TYPE) {
         exceptionState.throwTypeError("The result type is not an iterator.");
-        return 0;
+        return nullptr;
     }
 
     if (invalidIteratorState()) {
         exceptionState.throwDOMException(InvalidStateError, "The document has mutated since the result was returned.");
-        return 0;
+        return nullptr;
     }
 
     if (m_nodeSetPosition + 1 > nodeSet().size())
-        return 0;
+        return nullptr;
 
     Node* node = nodeSet()[m_nodeSetPosition];
 
@@ -209,12 +209,12 @@ Node* XPathResult::snapshotItem(unsigned index, ExceptionState& exceptionState)
 {
     if (resultType() != UNORDERED_NODE_SNAPSHOT_TYPE && resultType() != ORDERED_NODE_SNAPSHOT_TYPE) {
         exceptionState.throwTypeError("The result type is not a snapshot.");
-        return 0;
+        return nullptr;
     }
 
     const NodeSet& nodes = m_value.toNodeSet(0);
     if (index >= nodes.size())
-        return 0;
+        return nullptr;
 
     return nodes[index];
 }