V8 Buildbot: Fix dart mac builders.

scripts/slave/recipes/v8.expected/full_client_dart_fyi_v8_mac_release.json

Index: scripts/slave/recipes/v8.expected/full_client_dart_fyi_v8_mac_release.json
diff --git a/scripts/slave/recipes/v8.expected/full_client_dart_fyi_v8_mac_release.json b/scripts/slave/recipes/v8.expected/full_client_dart_fyi_v8_mac_release.json
index 65cf796a3ae55bcabffa878ec5a43db7114452f8..7909b09d81eebfc7a80754f7ccb5e47af5d80fe3 100644
--- a/scripts/slave/recipes/v8.expected/full_client_dart_fyi_v8_mac_release.json
+++ b/scripts/slave/recipes/v8.expected/full_client_dart_fyi_v8_mac_release.json
@@ -57,7 +57,8 @@
       "runhooks"
     ],
     "env": {
-      "GYP_DEFINES": "target_arch=ia32 v8_enable_disassembler=1 v8_target_arch=ia32"
+      "GYP_DEFINES": "clang=1 gomadir='[BUILD]/goma' target_arch=ia32 use_goma=1 v8_enable_disassembler=1 v8_target_arch=ia32",
+      "GYP_GENERATORS": "ninja"
     },
     "name": "gclient runhooks"
   },
@@ -79,7 +80,11 @@
       "--src-dir",
       "[SLAVE_BUILD]/v8",
       "--build-tool",
-      "xcode",
+      "ninja",
+      "--compiler",
+      "goma-clang",
+      "--goma-dir",
+      "[BUILD]/goma",
       "--"
     ],
     "name": "compile"