Don't include nacl_irt_x86_64.nexe in isolate for 32 bit Linux builds which don't have it.

chrome/chrome.isolate

 # Copyright (c) 2013 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.
 {
   'conditions': [
     ['OS=="linux"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/libffmpegsumo.so',
           '<(PRODUCT_DIR)/libosmesa.so',
@@ skipping 12 matching lines @@
     ['OS=="linux" or OS=="win"', {
       'variables': {
         'command': [
           '<(PRODUCT_DIR)/chrome<(EXECUTABLE_SUFFIX)',
         ],
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/chrome<(EXECUTABLE_SUFFIX)',
           '<(PRODUCT_DIR)/chrome_100_percent.pak',
           '<(PRODUCT_DIR)/locales/en-US.pak',
           '<(PRODUCT_DIR)/locales/fr.pak',
-          '<(PRODUCT_DIR)/nacl_irt_x86_64.nexe',
         ],
         'isolate_dependency_untracked': [
           '<(PRODUCT_DIR)/resources/extension/',
         ],
       },
     }],
+    ['OS=="win" or (OS=="linux" and target_arch=="x64")', {
+      'variables': {
+        'isolate_dependency_tracked': [
+          '<(PRODUCT_DIR)/nacl_irt_x86_64.nexe',
+        ],
+      },
+    }],
     ['OS=="mac"', {
       'variables': {
         'command': [
           '<(PRODUCT_DIR)/<(mac_product_name).app/Contents/MacOS/<(mac_product_name)',
         ],
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/exif.so',
           '<(PRODUCT_DIR)/ffmpegsumo.so',
         ],
         'isolate_dependency_untracked': [
@@ skipping 27 matching lines @@
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/chrome_child.dll',
         ],
       },
     }],
   ],
   'includes': [
     'angle.isolate',
   ],
 }