Revert "[vm] Implement more efficient CAS in simarm/simarm64 modes"

runtime/vm/vm_sources.gypi

 # Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # This file contains all sources (vm and tests) for the dart virtual machine.
 # Unit test files need to have a '_test' suffix appended to the name.
 {
   'sources': [
     'allocation.cc',
     'allocation.h',
@@ skipping 25 matching lines @@
     'ast_printer.h',
     'ast_printer_test.cc',
     'ast_test.cc',
     'ast_transformer.cc',
     'ast_transformer.h',
     'atomic.h',
     'atomic_android.h',
     'atomic_fuchsia.h',
     'atomic_linux.h',
     'atomic_macos.h',
+    'atomic_simulator.h',
     'atomic_test.cc',
     'atomic_win.h',
     'base_isolate.h',
     'become.h',
     'become.cc',
     'benchmark_test.cc',
     'benchmark_test.h',
     'bigint_test.cc',
     'bit_set_test.cc',
     'bit_vector.cc',
@@ skipping 495 matching lines @@
     'weak_code.h',
     'weak_table.cc',
     'weak_table.h',
     'zone.cc',
     'zone.h',
     'zone_test.cc',
     'zone_text_buffer.cc',
     'zone_text_buffer.h',
   ],
 }