{
  'targets': [
    {
      'target_name': 'time',
      'sources': [ 'src/time.cc' ],
      'conditions': [
        ['OS=="mac"', {
          'defines': [
            '__DARWIN_UNIX03', # For char* timezone
            'HAVE_TM_GMTOFF',  # TODO: Don't hardcode
            'HAVE_TIMEZONE'    # TODO: Don't hardcode
          ]
        }]
      ]
    }
  ]
}

@@ -234,87 +234,110 @@
 OFF'
-,  # TODO: Don't hardcode%0A            'HAVE_TIMEZONE'    # TODO: Don't hardcode
+%0A          %5D%0A        %7D%5D,%0A        %5B'OS==%22linux%22', %7B%0A          'defines': %5B%0A            'HAVE_TM_GMTOFF'
 %0A   

Add 'linux' defines.