Remove "this==NULL" and adjust corresponding callers

core/include/fpdfapi/fpdf_objects.h

 // 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
 
 #ifndef _FPDF_OBJECTS_
 #define _FPDF_OBJECTS_
 #ifndef _FXCRT_EXTENSION_
 #include "../fxcrt/fx_ext.h"
@@ skipping 602 matching lines @@
     void                                        LoadAllData(const CPDF_Stream* pStream, FX_BOOL bRawAccess = FALSE,
                                         FX_DWORD estimated_size = 0, FX_BOOL bImageAcc = FALSE);
 
     const CPDF_Stream*          GetStream() const
     {
         return m_pStream;
     }
 
     CPDF_Dictionary*            GetDict() const
     {
-        return m_pStream->GetDict();
+        return m_pStream? m_pStream->GetDict() : NULL;
     }
 
     FX_LPCBYTE                          GetData() const;
 
     FX_DWORD                            GetSize() const;
 
     FX_LPBYTE                           DetachData();
 
     const CFX_ByteString&       GetImageDecoder()
     {
@@ skipping 142 matching lines @@
     }
 protected:
 
     CFX_MapPtrToPtr                     m_IndirectObjs;
 
     IPDF_DocParser*                     m_pParser;
 
     FX_DWORD                            m_LastObjNum;
 };
 #endif