V8: Move gn-peek step behind mb step

scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux___presubmit.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "client.v8",
       "--builder",
       "V8 Linux - presubmit",
@@ skipping 57 matching lines @@
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json",
       "GYP_DEFINES": "target_arch=ia32 v8_target_arch=ia32",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[DEPOT_TOOLS]/gn.py",
-      "--root=[SLAVE_BUILD]/v8",
-      "gen",
-      "[TMP_BASE]/v8_gn_tmp_1",
-      "--args=is_debug=false target_cpu=\"x86\" use_goma=true goma_dir=\"None\""
-    ],
-    "name": "gn"
-  },
-  {
-    "cmd": [
-      "python",
-      "-u",
-      "[SLAVE_BUILD]/v8/tools/gyp_flag_compare.py",
-      "[TMP_BASE]/v8_gn_tmp_1",
-      "[SLAVE_BUILD]/v8/out/Release",
-      "all",
-      "all"
-    ],
-    "name": "compare build flags (fyi)"
-  },
-  {
-    "cmd": [
-      "python",
-      "-u",
-      "\nimport shutil, sys\nshutil.rmtree(sys.argv[1])\n",
-      "[TMP_BASE]/v8_gn_tmp_1"
-    ],
-    "name": "rmtree [TMP_BASE]/v8_gn_tmp_1",
-    "~followup_annotations": [
-      "@@@STEP_LOG_LINE@python.inline@@@@",
-      "@@@STEP_LOG_LINE@python.inline@import shutil, sys@@@",
-      "@@@STEP_LOG_LINE@python.inline@shutil.rmtree(sys.argv[1])@@@",
-      "@@@STEP_LOG_END@python.inline@@@"
-    ]
-  },
-  {
-    "cmd": [
-      "python",
-      "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/tools/runit.py",
       "--show-path",
       "python",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/cleanup_temp.py"
     ],
     "name": "cleanup_temp"
   },
   {
     "cmd": [
       "python",
@@ skipping 42 matching lines @@
     ],
     "cwd": "[SLAVE_BUILD]/v8",
     "name": "Presubmit"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]