Get rid of NULLs in xfa/

xfa/fxbarcode/pdf417/BC_PDF417DetectionResultColumn.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 // Original code is licensed as follows:
 /*
  * Copyright 2013 ZXing authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ skipping 42 matching lines @@
       }
     }
     nearImageRow = imageRowToCodewordIndex(imageRow) + i;
     if (nearImageRow < m_codewords->GetSize()) {
       codeword = (CBC_Codeword*)m_codewords->GetAt(nearImageRow);
       if (codeword) {
         return codeword;
       }
     }
   }
-  return NULL;
+  return nullptr;
 }
 int32_t CBC_DetectionResultColumn::imageRowToCodewordIndex(int32_t imageRow) {
   return imageRow - m_boundingBox->getMinY();
 }
 int32_t CBC_DetectionResultColumn::codewordIndexToImageRow(
     int32_t codewordIndex) {
   return m_boundingBox->getMinY() + codewordIndex;
 }
 void CBC_DetectionResultColumn::setCodeword(int32_t imageRow,
                                             CBC_Codeword* codeword) {
   m_codewords->SetAt(imageRowToCodewordIndex(imageRow), codeword);
 }
 CBC_Codeword* CBC_DetectionResultColumn::getCodeword(int32_t imageRow) {
   return (CBC_Codeword*)m_codewords->GetAt(imageRowToCodewordIndex(imageRow));
 }
 CBC_BoundingBox* CBC_DetectionResultColumn::getBoundingBox() {
   return m_boundingBox;
 }
 CFX_ArrayTemplate<CBC_Codeword*>* CBC_DetectionResultColumn::getCodewords()
     const {
   return m_codewords;
 }
 CFX_ByteString CBC_DetectionResultColumn::toString() {
   CFX_ByteString result;
   int32_t row = 0;
   for (int32_t i = 0; i < m_codewords->GetSize(); i++) {
     CBC_Codeword* codeword = (CBC_Codeword*)m_codewords->GetAt(i);
-    if (codeword == NULL) {
+    if (!codeword) {
       result += (FX_CHAR)row;
       row++;
       continue;
     }
     result += (FX_CHAR)row;
     result += codeword->getRowNumber();
     result += codeword->getValue();
     row++;
   }
   return result;
 }