Bug 1407432 - Remove unused builtins arg from Sandbox; r=froydnj

MozReview-Commit-ID: JVukxIg04AT

--HG--
extra : source : bacf04be0a480e4d7ea94de3c2677de3e0d5e10c

python/mozbuild/mozbuild/frontend/sandbox.py

@@ -113,10 +113,10 @@ class Sandbox(dict):
         'set': set,
     })
 
-    def __init__(self, context, builtins=None, finder=default_finder):
+    def __init__(self, context, finder=default_finder):
         """Initialize a Sandbox ready for execution.
         """
-        self._builtins = builtins or self.BUILTINS
+        self._builtins = self.BUILTINS
         dict.__setitem__(self, '__builtins__', self._builtins)
 
         assert isinstance(self._builtins, ReadOnlyDict)