Remove requirement that mojo::Environment be instantiated.

mojo/public/python/mojo_system_impl.pyx

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # distutils language = c++
 
 cimport c_async_waiter
 cimport c_environment
 cimport c_export  # needed so the init function gets exported
 cimport c_thunks
@@ skipping 39 matching lines @@
     Post a task on the runloop. This must be called from the thread owning the
     runloop.
     """
     cdef c_environment.CClosure closure = c_environment.BuildClosure(runnable)
     self.c_run_loop.PostDelayedTask(closure, delay)
 
 
 # We use a wrapping class to be able to call the C++ class PythonAsyncWaiter
 # across module boundaries.
 cdef class AsyncWaiter(object):
-  cdef c_environment.CEnvironment* _cenvironment
   cdef c_async_waiter.PythonAsyncWaiter* _c_async_waiter
 
   def __init__(self):
-    self._cenvironment = new c_environment.CEnvironment()
     self._c_async_waiter = c_environment.NewAsyncWaiter()
 
   def __dealloc__(self):
     del self._c_async_waiter
-    del self._cenvironment
 
   def AsyncWait(self, handle, signals, deadline, callback):
     return self._c_async_waiter.AsyncWait(handle, signals, deadline, callback)
 
   def CancelWait(self, wait_id):
     self._c_async_waiter.CancelWait(wait_id)