Fix an integer overflow in CStretchEngine constructor

core/fxge/dib/fx_dib_engine.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 <limits.h>
 
 #include <algorithm>
 
@@ skipping 288 matching lines @@
   m_ExtraMaskPitch = (m_DestClip.Width() * 8 + 31) / 32 * 4;
   m_pInterBuf = nullptr;
   m_pSource = pSrcBitmap;
   m_SrcWidth = pSrcBitmap->GetWidth();
   m_SrcHeight = pSrcBitmap->GetHeight();
   m_SrcPitch = (m_SrcWidth * m_SrcBpp + 31) / 32 * 4;
   if ((flags & FXDIB_NOSMOOTH) == 0) {
     FX_BOOL bInterpol =
         flags & FXDIB_INTERPOL || flags & FXDIB_BICUBIC_INTERPOL;
     if (!bInterpol && FXSYS_abs(dest_width) != 0 &&
-        FXSYS_abs(dest_height) <
-            m_SrcWidth * m_SrcHeight * 8 / FXSYS_abs(dest_width)) {
+        FXSYS_abs(dest_height) / 8 < static_cast<long long>(m_SrcWidth) *
+                                         m_SrcHeight / FXSYS_abs(dest_width)) {
       flags = FXDIB_INTERPOL;
     }
     m_Flags = flags;
   } else {
     m_Flags = FXDIB_NOSMOOTH;
     if (flags & FXDIB_DOWNSAMPLE) {
       m_Flags |= FXDIB_DOWNSAMPLE;
     }
   }
   double scale_x = (FX_FLOAT)m_SrcWidth / (FX_FLOAT)m_DestWidth;
@@ skipping 673 matching lines @@
                                   result_width);
     if (m_pMaskScanline) {
       m_pSource->m_pAlphaMask->DownSampleScanline(
           src_y, m_pMaskScanline.get(), 1, m_DestWidth, m_bFlipX,
           m_ClipRect.left, result_width);
     }
     m_pDest->ComposeScanline(dest_y, m_pScanline.get(), m_pMaskScanline.get());
   }
   return FALSE;
 }