Roll recipe dependencies (nontrivial).

scripts/slave/recipes/flutter/flutter.expected/mac_cannot_find_xcode.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport os, sys\nfrom common import chromium_utils # Error? See https://crbug.com/584783.\n\npath = sys.argv[1]\nif os.path.exists(path):\n  for p in (os.path.join(path, x) for x in os.listdir(path)):\n    if os.path.isdir(p):\n      chromium_utils.RemoveDirectory(p)\n    else:\n      os.unlink(p)\n",
       "[SLAVE_BUILD]"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "rmcontents everything",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import os, sys@@@",
       "@@@STEP_LOG_LINE@python.inline@from common import chromium_utils # Error? See https://crbug.com/584783.@@@",
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@path = sys.argv[1]@@@",
       "@@@STEP_LOG_LINE@python.inline@if os.path.exists(path):@@@",
       "@@@STEP_LOG_LINE@python.inline@  for p in (os.path.join(path, x) for x in os.listdir(path)):@@@",
       "@@@STEP_LOG_LINE@python.inline@    if os.path.isdir(p):@@@",
       "@@@STEP_LOG_LINE@python.inline@      chromium_utils.RemoveDirectory(p)@@@",
       "@@@STEP_LOG_LINE@python.inline@    else:@@@",
       "@@@STEP_LOG_LINE@python.inline@      os.unlink(p)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::git]/resources/git_setup.py",
       "--path",
       "[SLAVE_BUILD]/flutter",
       "--url",
       "https://chromium.googlesource.com/external/github.com/flutter/flutter"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "git setup"
   },
   {
     "cmd": [
       "git",
       "retry",
       "fetch",
       "origin",
       "master",
       "--recurse-submodules"
@@ skipping 53 matching lines @@
       "--init",
       "--recursive"
     ],
     "cwd": "[SLAVE_BUILD]/flutter",
     "name": "submodule update"
   },
   {
     "cmd": [
       "[SLAVE_BUILD]/flutter/infra/download_android_tools.py"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "download android tools"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/ios/find_xcode.py",
       "--json-file",
       "/path/to/tmp/json"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "env": {
       "ANDROID_HOME": "[SLAVE_BUILD]/flutter/infra/android_tools",
       "PATH": "[SLAVE_BUILD]/flutter/bin:[SLAVE_BUILD]/flutter/bin/cache/dart-sdk/bin:%(PATH)s",
       "PUB_CACHE": "[SLAVE_BUILD]/.pub-cache"
     },
     "name": "enumerate_xcode_installations",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"installations\": {}@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "name": "$result",
     "reason": "Xcode version 7 or above not found",
     "status_code": 1
   }
 ]