Revert "Remove FX_Alloc() null checks now that it can't return NULL."

core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.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 "../../../include/fpdfapi/fpdf_parser.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../src/fxcrt/fx_safe_types.h"
@@ skipping 2459 matching lines @@
                 m_Pos = StreamStartPos;
                 if (FindTag(FX_BSTRC("endobj"), 0) < 0) {
                     return NULL;
                 }
             }
         }
         m_Pos = StreamStartPos;
     }
     CPDF_Stream* pStream;
     FX_LPBYTE pData = FX_Alloc(FX_BYTE, len);
+    if (!pData) {
+        return NULL;
+    }
     ReadBlock(pData, len);
     if (pCryptoHandler) {
         CFX_BinaryBuf dest_buf;
         dest_buf.EstimateSize(pCryptoHandler->DecryptGetSize(len));
         FX_LPVOID context = pCryptoHandler->DecryptStart(objnum, gennum);
         pCryptoHandler->DecryptStream(context, pData, len, dest_buf);
         pCryptoHandler->DecryptFinish(context, dest_buf);
         FX_Free(pData);
         pData = dest_buf.GetBuffer();
         len = dest_buf.GetSize();
@@ skipping 2149 matching lines @@
 {
     FX_INT32 iSize = m_childNode.GetSize();
     for (FX_INT32 i = 0; i < iSize; ++i) {
         CPDF_PageNode *pNode = (CPDF_PageNode*)m_childNode[i];
         if (pNode) {
             delete pNode;
         }
     }
     m_childNode.RemoveAll();
 }