Add type cast definitions for CPDF_Array.

fpdfsdk/src/fpdfview.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
 
 #include "../../core/include/fxcodec/fx_codec.h"
 #include "../../core/include/fxcrt/fx_safe_types.h"
 #include "../../public/fpdf_ext.h"
 #include "../../public/fpdf_progressive.h"
@@ skipping 863 matching lines @@
       if (!pDestObj)
         continue;
       if (i == index)
         break;
       i++;
     }
   } else {
     pDestObj = nameTree.LookupValue(index, bsName);
   }
   if (!pDestObj)
-    return NULL;
+    return nullptr;
   if (CPDF_Dictionary* pDict = pDestObj->AsDictionary()) {
     pDestObj = pDict->GetArray(FX_BSTRC("D"));
     if (!pDestObj)
-      return NULL;
+      return nullptr;
   }
-  if (pDestObj->GetType() != PDFOBJ_ARRAY)
-    return NULL;
+  if (!pDestObj->IsArray())
+    return nullptr;
+
   CFX_WideString wsName = PDF_DecodeText(bsName);
   CFX_ByteString utf16Name = wsName.UTF16LE_Encode();
   unsigned int len = utf16Name.GetLength();
   if (!buffer) {
     *buflen = len;
   } else if (*buflen >= len) {
     memcpy(buffer, utf16Name.c_str(), len);
     *buflen = len;
   } else {
     *buflen = -1;
   }
   return (FPDF_DEST)pDestObj;
 }