Use icu_gyp_path variable to reference ICU gyp file

src/d8.gyp

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 63 matching lines @@
             }],
           ],
         }],
         ['v8_enable_vtunejit==1', {
           'dependencies': [
             '../src/third_party/vtune/v8vtune.gyp:v8_vtune',
           ],
         }],
         ['v8_enable_i18n_support==1', {
           'dependencies': [
-            '<(DEPTH)/third_party/icu/icu.gyp:icui18n',
-            '<(DEPTH)/third_party/icu/icu.gyp:icuuc',
+            '<(icu_gyp_path):icui18n',
+            '<(icu_gyp_path):icuuc',
           ],
         }],
         ['OS=="win" and v8_enable_i18n_support==1', {
           'dependencies': [
-            '<(DEPTH)/third_party/icu/icu.gyp:icudata',
+            '<(icu_gyp_path):icudata',
           ],
         }],
       ],
     },
     {
       'target_name': 'd8_js2c',
       'type': 'none',
       'variables': {
         'js_files': [
           'd8.js',
@@ skipping 23 matching lines @@
             '<@(_outputs)',
             'D8',
             'off',  # compress startup data
             '<@(js_files)'
           ],
         },
       ],
     }
   ],
 }