WIP (Introduce WTF::NonNullPtr<T>.)

Source/core/xml/XPathFunctions.cpp

 /*
  * Copyright (C) 2005 Frerich Raabe <raabe@kde.org>
  * Copyright (C) 2006, 2009 Apple Inc.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 312 matching lines @@
         for (size_t i = 0; i < nodes.size(); ++i) {
             String str = stringValue(nodes[i]);
             idList.append(str);
             idList.append(' ');
         }
     } else {
         String str = a.toString();
         idList.append(str);
     }
 
-    TreeScope& contextScope = evaluationContext().node->treeScope();
+    NonNullPtr<TreeScope> contextScope = evaluationContext().node->treeScope();
     NodeSet result;
     HashSet<Node*> resultSet;
 
     unsigned startPos = 0;
     unsigned length = idList.length();
     while (true) {
         while (startPos < length && isWhitespace(idList[startPos]))
             ++startPos;
 
         if (startPos == length)
             break;
 
         size_t endPos = startPos;
         while (endPos < length && !isWhitespace(idList[endPos]))
             ++endPos;
 
         // If there are several nodes with the same id, id() should return the first one.
         // In WebKit, getElementById behaves so, too, although its behavior in this case is formally undefined.
-        Node* node = contextScope.getElementById(idList.substring(startPos, endPos - startPos));
+        Node* node = contextScope->getElementById(idList.substring(startPos, endPos - startPos));
         if (node && resultSet.add(node).isNewEntry)
             result.append(node);
 
         startPos = endPos;
     }
 
     result.markSorted(false);
 
     return Value(result, Value::adopt);
 }
@@ skipping 361 matching lines @@
         return 0;
 
     Function* function = functionRec->factoryFn();
     function->setArguments(args);
     function->setName(name);
     return function;
 }
 
 }
 }