Convert from using env['PLATFORM'] directly to using the more flexible...

chrome/tools/test/image_diff/image_diff.scons

 # Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 Import('env')
 
 env = env.Clone()
 
 env.ApplySConscript([
     '$BASE_DIR/using_base.scons',
     '$BASE_DIR/gfx/using_base_gfx.scons',
     '$ICU38_DIR/using_icu38.scons',
     '$LIBPNG_DIR/using_libpng.scons',
     '$SKIA_DIR/using_skia.scons',
     '$ZLIB_DIR/using_zlib.scons',
 ])
 
 env.Prepend(
     CPPPATH = [
         '$CHROME_SRC_DIR',
     ],
 )
 
-if env['PLATFORM'] == 'win32':
+if env.Bit('windows'):
     env.Prepend(
         LINKFLAGS = [
             '/INCREMENTAL',
             '/DEBUG',
 
             '/DELAYLOAD:"dwmapi.dll"',
             '/DELAYLOAD:"uxtheme.dll"',
 
             '/SUBSYSTEM:CONSOLE',
 
             '/MACHINE:X86',
             '/FIXED:No',
 
             '/safeseh',
             '/dynamicbase',
             '/ignore:4199',
             '/nxcompat',
         ],
     )
 
 input_files = [
     'image_diff.cc',
 ]
 
 env.ChromeTestProgram('image_diff', input_files)