Roll recipe dependencies (nontrivial).

scripts/slave/recipes/ios/unified_builder_tester.expected/goma.json

 [
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/ios/host_info.py",
       "--json-file",
       "/path/to/tmp/json"
     ],
     "name": "host and tools info",
     "~followup_annotations": [
       "@@@STEP_TEXT@<br />OS X 1.2.3, Xcode 6.7.8 (5D342509a)@@@",
@@ skipping 157 matching lines @@
   },
   {
     "cmd": [
       "echo",
       "-e",
       "{\n  \"GYP_DEFINES\": {\n    \"OS\": \"ios\", \n    \"component\": \"static_library\", \n    \"fake gyp define 1\": \"fake value 1\", \n    \"fake gyp define 2\": \"fake value 2\", \n    \"use_goma\": \"1\"\n  }, \n  \"additional_compile_targets\": [\n    \"All\"\n  ], \n  \"configuration\": \"Release\", \n  \"env\": {}, \n  \"gn_args\": [], \n  \"mastername\": \"chromium.fake\", \n  \"mb_type\": null, \n  \"sdk\": \"iphoneos8.0\", \n  \"tests\": [], \n  \"triggered bots\": {}, \n  \"use_analyze\": true, \n  \"xcode version\": \"fake xcode version\"\n}"
     ],
     "name": "finalize build config"
   },
   {
-    "cmd": [],
     "name": "ensure_goma"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::cipd]/resources/bootstrap.py",
       "--platform",
       "mac-amd64",
       "--dest-directory",
@@ skipping 145 matching lines @@
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]