Fix build breakage (partially revert r2327

runtime/vm/vm_sources.gypi

 # Copyright (c) 2011, 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 108 matching lines @@
     'handles_impl.h',
     'handles_test.cc',
     'heap.cc',
     'heap.h',
     'heap_test.cc',
     'ic_data.h',
     'ic_data.cc',
     'ic_data_test.cc',
     'inttypes_support_win.h',
     'instructions.h',
+    'instructions_ia32.h',
     'instructions_ia32.cc',
-    'instructions_ia32.h',
     'instructions_ia32_test.cc',
-    'instructions_x64.cc',
-    'instructions_x64.h',
-    'instructions_x64_test.cc',
     'intrinsifier.h',
     'intrinsifier_ia32.cc',
     'intrinsifier_x64.cc',
     'intrinsifier_arm.cc',
     'isolate.cc',
     'isolate.h',
     'isolate_linux.cc',
     'isolate_linux.h',
     'isolate_macos.cc',
     'isolate_macos.h',
@@ skipping 111 matching lines @@
     'virtual_memory_test.cc',
     'virtual_memory_win.cc',
     'verifier.cc',
     'verifier.h',
     'visitor.h',
     'zone.cc',
     'zone.h',
     'zone_test.cc',
   ],
 }