Add type cast definitions for CPDF_Stream.

core/src/fpdfapi/fpdf_render/fpdf_render_image.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_module.h"
 #include "../../../include/fpdfapi/fpdf_pageobj.h"
 #include "../../../include/fpdfapi/fpdf_render.h"
 #include "../../../include/fxcodec/fx_codec.h"
@@ skipping 1037 matching lines @@
   int width = pClipRect->right - pClipRect->left;
   int height = pClipRect->bottom - pClipRect->top;
   FX_BOOL bLuminosity = FALSE;
   bLuminosity = pSMaskDict->GetConstString(FX_BSTRC("S")) != FX_BSTRC("Alpha");
   CPDF_Stream* pGroup = pSMaskDict->GetStream(FX_BSTRC("G"));
   if (pGroup == NULL) {
     return NULL;
   }
   CPDF_Function* pFunc = NULL;
   CPDF_Object* pFuncObj = pSMaskDict->GetElementValue(FX_BSTRC("TR"));
-  if (pFuncObj &&
-      (pFuncObj->IsDictionary() || pFuncObj->GetType() == PDFOBJ_STREAM)) {
+  if (pFuncObj && (pFuncObj->IsDictionary() || pFuncObj->IsStream()))
     pFunc = CPDF_Function::Load(pFuncObj);
-  }
+
   CFX_AffineMatrix matrix = *pMatrix;
   matrix.TranslateI(-pClipRect->left, -pClipRect->top);
   CPDF_Form form(m_pContext->m_pDocument, m_pContext->m_pPageResources, pGroup);
   form.ParseContent(NULL, NULL, NULL, NULL);
   CFX_FxgeDevice bitmap_device;
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
   if (!bitmap_device.Create(width, height,
                             bLuminosity ? FXDIB_Rgb32 : FXDIB_8bppMask)) {
     return NULL;
   }
@@ skipping 94 matching lines @@
     for (int i = 0; i < size; i++) {
       dest_buf[i] = pTransfer[src_buf[i]];
     }
   } else {
     FXSYS_memcpy(dest_buf, src_buf, dest_pitch * height);
   }
   delete pFunc;
   FX_Free(pTransfer);
   return pMask;
 }