NaCl: Enable untrusted hardware exception handling by default

ppapi/native_client/tests/nacl_browser/inbrowser_test_runner/nacl.scons

 # -*- python -*-
 # Copyright (c) 2012 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.
 
 import json
 import posixpath
 
 Import('env')
 
-# Enable untrusted exception handling (for exception_test).
-env['ENV']['NACL_UNTRUSTED_EXCEPTION_HANDLING'] = '1'
-
 env.ComponentLibrary('testrunner_browser', ['test_runner_ppapi.c'])
 
 dest_copy = env.Replicate('$STAGING_DIR', 'test_runner.html')
 env.Replicate('$STAGING_DIR',
               '${SCONSTRUCT_DIR}/tools/browser_tester/browserdata/nacltest.js')
 
 def AddTest(env, test_name, exe_list, parallel=False):
   test_files = [env.File('${STAGING_DIR}/%s${PROGSUFFIX}'
                          % env.ProgramNameForNmf(exe_name))
                 for exe_name in exe_list]
@@ skipping 30 matching lines @@
   # inbrowser_test_runner_parallel is flaky on 32 bit windows
   # (maybe http://code.google.com/p/chromium/issues/detail?id=120355 ?)
                                    parallel)
 
 if not env.Bit('tests_use_irt'):
   Return()
 
 exe_list = env['TESTS_TO_RUN_INBROWSER']
 AddTest(env, 'run_inbrowser_test_runner', exe_list, parallel=False)
 AddTest(env, 'run_inbrowser_test_runner_parallel', exe_list, parallel=True)