Revert "Avoid to use environment."

scripts/slave/recipes/dart/dartium_build.expected/basic_win_64_MirrorTrue.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[depot_tools]\\gclient.py",
       "config",
       "--spec",
       "cache_dir = '[GIT_CACHE]'\nsolutions = [{'custom_vars': {'dartium_base': 'svn://svn-mirror.golo.chromium.org'}, 'deps_file': '.DEPS.git', 'managed': True, 'name': 'dartium.deps', 'url': 'svn://svn-mirror.golo.chromium.org/dart/branches/bleeding_edge/deps/dartium.deps'}]"
     ],
@@ skipping 124 matching lines @@
       "--gsutil-py-path",
       "RECIPE_PACKAGE_REPO[depot_tools]\\gsutil.py",
       "--ninja-path",
       "RECIPE_PACKAGE_REPO[depot_tools]\\ninja.exe",
       "--target",
       "Release_x64",
       "--src-dir",
       "[SLAVE_BUILD]\\src",
       "--goma-cache-dir",
       "[GOMA_CACHE]",
-      "--buildbot-buildername",
-      "TestBuilder",
-      "--buildbot-mastername",
-      "chromium.testing.master",
-      "--buildbot-slavename",
-      "TestSlavename",
       "--compiler",
       "goma",
       "--goma-jsonstatus",
       "/path/to/tmp/json",
       "--goma-service-account-json-file",
       "C:\\creds\\service_accounts\\service-account-goma-client.json",
       "--goma-dir",
       "[BUILD]\\goma",
       "--",
       "All",
@@ skipping 16 matching lines @@
       "12345"
     ],
     "name": "archive_build"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]