Roll recipe dependencies (nontrivial).

scripts/slave/recipes/webrtc/ios.expected/gn_build.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 144 matching lines @@
       "GYP_GENERATORS": "ninja",
       "LANDMINES_VERBOSE": "1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks",
     "~followup_annotations": [
       "@@@STEP_TEXT@<br />GYP_DEFINES:<br />component=static_library<br />OS=ios<br />GYP_CHROMIUM_NO_ACTION=1@@@"
     ]
   },
   {
-    "cmd": [],
     "name": "ensure_goma"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::cipd]/resources/bootstrap.py",
       "--platform",
       "mac-amd64",
       "--dest-directory",
@@ skipping 74 matching lines @@
     ],
     "cwd": "[BUILDER_CACHE]/ios/src/out/Debug-iphoneos",
     "name": "compile"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]