Fix an integer overflow in CStretchEngine constructor

pdfium.gyp

 # Copyright 2015 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'pdf_use_skia%': 0,
     'pdf_enable_v8%': 1,
     'pdf_enable_xfa%': 0, # Set to 1 by standalone.gypi in a standalone build.
@@ skipping 927 matching lines @@
         'core/fpdftext/fpdf_text_int_unittest.cpp',
         'core/fxcodec/codec/fx_codec_jpx_unittest.cpp',
         'core/fxcrt/fx_basic_bstring_unittest.cpp',
         'core/fxcrt/fx_basic_gcc_unittest.cpp',
         'core/fxcrt/fx_basic_memmgr_unittest.cpp',
         'core/fxcrt/fx_basic_util_unittest.cpp',
         'core/fxcrt/fx_basic_wstring_unittest.cpp',
         'core/fxcrt/fx_bidi_unittest.cpp',
         'core/fxcrt/fx_extension_unittest.cpp',
         'core/fxcrt/fx_system_unittest.cpp',
+        'core/fxge/dib/fx_dib_engine_unittest.cpp',
         'fpdfsdk/fpdfdoc_unittest.cpp',
         'fpdfsdk/fpdfeditimg_unittest.cpp',
         'testing/fx_string_testhelpers.h',
         'testing/fx_string_testhelpers.cpp',
       ],
       'conditions': [
         ['pdf_enable_xfa==1', {
           'sources': [
             'xfa/fde/css/fde_cssdatatable.cpp',
             'xfa/fde/xml/fde_xml_imp_unittest.cpp',
@@ skipping 168 matching lines @@
             'fpdfsdk/fpdfxfa/include/fpdfxfa_app.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_doc.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_page.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_util.h',
           ],
         },
       ]
     }],
   ]
 }