Re-enable DepsCache using GOMA_DEPS_CACHE_FILE

scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_win_swarming.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys, os\npath = sys.argv[1]\nmode = int(sys.argv[2])\nif not os.path.isdir(path):\n  if os.path.exists(path):\n    print \"%s exists but is not a dir\" % path\n    sys.exit(1)\n  os.makedirs(path, mode)\n",
       "[BUILDER_CACHE]\\win_swarming",
       "511"
     ],
     "name": "makedirs checkout path",
@@ skipping 246 matching lines @@
       "--src-dir",
       "[BUILDER_CACHE]\\win_swarming\\src",
       "--goma-cache-dir",
       "[GOMA_CACHE]",
       "--buildbot-buildername",
       "win_swarming",
       "--buildbot-mastername",
       "tryserver.webrtc",
       "--buildbot-slavename",
       "slavename",
-      "--goma-deps-cache-dir",
-      "[GOMA_DEPS_CACHE]",
+      "--goma-deps-cache-file",
+      "win_swarming.gomadeps",
       "--compiler",
       "goma",
       "--goma-jsonstatus",
       "/path/to/tmp/json",
       "--goma-service-account-json-file",
       "C:\\creds\\service_accounts\\service-account-goma-client.json",
       "--goma-dir",
       "[CACHE]\\cipd\\goma",
       "--goma-fail-fast",
       "--goma-disable-local-fallback",
@@ skipping 3132 matching lines @@
       "@@@STEP_LOG_END@json.output@@@",
       "@@@STEP_LINK@shard #0 isolated out@blah@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]