NaCl/GYP: remove references to prep_toolchain.

gpu/command_buffer/command_buffer_nacl.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     '../../build/common_untrusted.gypi',
     'command_buffer.gypi',
   ],
   'conditions': [
     ['disable_nacl==0 and disable_nacl_untrusted==0', {
       'targets': [
         {
           'target_name': 'gles2_utils_nacl',
           'type': 'none',
           'variables': {
             'gles2_utils_target': 1,
             'nacl_untrusted_build': 1,
             'nlib_target': 'libgles2_utils_nacl.a',
             'build_glibc': 0,
             'build_newlib': 0,
             'build_irt': 1,
             'build_pnacl_newlib': 0,
             'build_nonsfi_helper': 1,
           },
           'dependencies': [
-            '../../native_client/tools.gyp:prep_toolchain',
             '../../base/base_nacl.gyp:base_nacl',
             '../../base/base_nacl.gyp:base_nacl_nonsfi',
             '../../third_party/khronos/khronos.gyp:khronos_headers',
           ],
         },
       ],
     }],
   ],
 }