Don't make clang plugins stuff dependent on _toolset=target either.

build/common.gypi

 # Copyright (c) 2011 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 1515 matching lines @@
               # http://code.google.com/p/googletest/source/detail?r=446 .
               # TODO(thakis): Use -isystem instead (http://crbug.com/58751 )
               '-Wno-unnamed-type-template-args',
             ],
             'cflags!': [
               # Clang doesn't seem to know know this flag.
               '-mfpmath=sse',
             ],
           }],
           ['clang==1 and clang_use_chrome_plugins==1', {
-            'target_conditions': [
-              ['_toolset=="target"', {
-                'cflags': [
-                  '<(clang_chrome_plugins_flags)',
-                ],
-              }]],
+            'cflags': [
+              '<(clang_chrome_plugins_flags)',
+            ],
           }],
           ['clang==1 and clang_load!="" and clang_add_plugin!=""', {
-            'target_conditions': [
-              ['_toolset=="target"', {
-                'cflags': [
-                  '-Xclang', '-load', '-Xclang', '<(clang_load)',
-                  '-Xclang', '-add-plugin', '-Xclang', '<(clang_add_plugin)',
-                ],
-              }]],
+            'cflags': [
+              '-Xclang', '-load', '-Xclang', '<(clang_load)',
+              '-Xclang', '-add-plugin', '-Xclang', '<(clang_add_plugin)',
+            ],
           }],
           ['no_strict_aliasing==1', {
             'cflags': [
               '-fno-strict-aliasing',
             ],
           }],
           ['linux_breakpad==1', {
             'cflags': [ '-g' ],
             'defines': ['USE_LINUX_BREAKPAD'],
           }],
@@ skipping 385 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',
   },
 }