Remove another now-unnecessary msvs_cygwin_shell:1

chrome/installer/mini_installer.gyp

 {
   'variables': {
     'version_py': '../../chrome/tools/build/version.py',
     'version_path': '../../chrome/VERSION',
     'lastchange_path': '<(DEPTH)/build/util/LASTCHANGE',
     # 'branding_dir' is set in the 'conditions' section at the bottom.
     'msvs_use_common_release': 0,
     'msvs_use_common_linker_extras': 0,
     'mini_installer_internal_deps%': 0,
     'mini_installer_official_deps%': 0,
@@ skipping 243 matching lines @@
                 '<(target_arch_flag)',
                 # TODO(sgk):  may just use environment variables
                 #'--distribution=$(CHROMIUM_BUILD)',
                 '--distribution=_google_chrome',
                 # Optional arguments to generate diff installer
                 #'--last_chrome_installer=C:/Temp/base',
                 #'--setup_exe_format=DIFF',
                 #'--diff_algorithm=COURGETTE',
               ],
               'message': 'Create installer archive',
-              'msvs_cygwin_shell': 1,
             },
           ],
           # TODO(mark):  <(branding_dir) should be defined by the
           # global condition block at the bottom of the file, but
           # this doesn't work due to the following issue:
           #
           #   http://code.google.com/p/gyp/issues/detail?id=22
           #
           # Remove this block once the above issue is fixed.
           'conditions': [
@@ skipping 34 matching lines @@
       'variables': {
          'branding_dir': '../app/theme/google_chrome',
       },
     }, { # else branding!="Chrome"
       'variables': {
          'branding_dir': '../app/theme/chromium',
       },
     }],
   ],
 }