Exclude spellcheck related code properly on android/ios which doesn't have spellchecker

build/common.gypi

 # 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 793 matching lines @@
           'enable_webrtc%': 1,
         }],
 
         ['OS=="ios"', {
           'disable_ftp_support%': 1,
           'enable_extensions%': 0,
           'enable_google_now%': 0,
           'cld_version%': 1,
           'enable_printing%': 0,
           'enable_session_service%': 0,
+          'enable_spellcheck%': 0,
           'enable_themes%': 0,
           'enable_webrtc%': 0,
           'notifications%': 0,
           'remoting%': 0,
           'safe_browsing%': 0,
           'enable_managed_users%': 0,
           'enable_task_manager%': 0,
           'use_system_libcxx%': 1,
           'support_pre_M6_history_database%': 0,
         }],
@@ skipping 5064 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }