Revert r34736 due to slowdown.

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 331 matching lines @@
     'simulator_arm.cc',
     'simulator_arm.h',
     'simulator_arm64.cc',
     'simulator_arm64.h',
     'simulator_mips.cc',
     'simulator_mips.h',
     'snapshot.cc',
     'snapshot.h',
     'snapshot_ids.h',
     'snapshot_test.cc',
-    'spaces.h',
     'stack_frame.cc',
     'stack_frame.h',
     'stack_frame_arm.h',
     'stack_frame_arm64.h',
     'stack_frame_ia32.h',
     'stack_frame_mips.h',
     'stack_frame_test.cc',
     'stack_frame_x64.h',
     'store_buffer.cc',
     'store_buffer.h',
@@ skipping 51 matching lines @@
     'visitor.h',
     'vtune.cc',
     'vtune.h',
     'weak_table.cc',
     'weak_table.h',
     'zone.cc',
     'zone.h',
     'zone_test.cc',
   ],
 }