Recipes: make cwd default to slave_build

scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux64.json

Index: scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux64.json
diff --git a/scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux64.json b/scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux64.json
index 2e02be3ee39789f3383f3f50ba0c060227afdde8..54382f3b81fde1404739b64c8adf867f9cd4dd35 100644
--- a/scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux64.json
+++ b/scripts/slave/recipes/v8.expected/full_client_v8_V8_Linux64.json
@@ -23,6 +23,7 @@
       "--no_shallow",
       "--output_manifest"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -55,6 +56,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "target_arch=x64 v8_target_arch=x64"
     },
@@ -66,6 +68,7 @@
       "-u",
       "[BUILD]/scripts/slave/cleanup_temp.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "cleanup_temp"
   },
   {
@@ -75,6 +78,7 @@
       "\nimport os, sys\nfrom common import chromium_utils\n\nif os.path.exists(sys.argv[1]):\n  chromium_utils.RemoveDirectory(sys.argv[1])\n",
       "[SLAVE_BUILD]/v8/out/Release"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "rmtree build directory",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
@@ -102,6 +106,7 @@
       "--build-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"branch\": \"master\", \"buildername\": \"V8 Linux64\", \"buildnumber\": 571, \"mastername\": \"client.v8\", \"parent_buildername\": \"V8 Linux64 - builder\", \"parent_got_revision\": \"54321\", \"recipe\": \"v8\", \"revision\": \"20123\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "extract build"
   },
   {