Stop passing --build-tool=ninja in master configs

scripts/master/factory/dart/dart_factory.py

Index: scripts/master/factory/dart/dart_factory.py
diff --git a/scripts/master/factory/dart/dart_factory.py b/scripts/master/factory/dart/dart_factory.py
index 1a04a4f6a7745cdb489b8fc747bad47836631578..ca03864baed293c625d849535efb8598e76c4d24 100644
--- a/scripts/master/factory/dart/dart_factory.py
+++ b/scripts/master/factory/dart/dart_factory.py
@@ -332,11 +332,9 @@ class PackageFactory(gclient_factory.GClientFactory):
 
 
 class DartUtils(object):
-  mac_options = ['--compiler=goma-clang',

[Nico, 2016/06/23 16:58:28]

goma-clang and goma mean the same thing these days, so changing this too while
i'm here

-                 '--build-tool=ninja',
-                 'dartium_builder']
-  linux_options = ['--compiler=goma', '--build-tool=ninja', 'dartium_builder']
-  win_options = ['--build-tool=ninja', 'dartium_builder']
+  mac_options = ['--compiler=goma', 'dartium_builder']
+  linux_options = ['--compiler=goma', 'dartium_builder']
+  win_options = ['dartium_builder']
 
 
   win_rel_factory_properties = {