Remove override of --mmacosx-version-min when building iossim.

testing/iossim/BUILD.gn

 # Copyright 2016 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.
 
 import("//build/config/mac/mac_sdk.gni")
 
 if (current_toolchain == host_toolchain) {
-  config("config") {
-    visibility = [ ":iossim" ]
-
-    include_dirs = [ "$root_gen_dir/iossim" ]
-
-    # -objectForKeyedSubscript requires 10.8 or newer. Remove this override once
-    # the global version of the SDK is raised.
-    common_flags = [ "-mmacosx-version-min=10.8" ]
-    ldflags = common_flags
-    cflags_objcc = common_flags
-  }
-
   executable("iossim") {
     sources = [
       "iossim.mm",
     ]
     libs = [ "Foundation.framework" ]
-    configs += [ ":config" ]
   }
 } else if (current_toolchain == default_toolchain) {
   copy("iossim") {
     deps = [
       ":iossim($host_toolchain)",
     ]
     outputs = [
       "$root_out_dir/iossim",
     ]
     sources = [
       get_label_info(":iossim($host_toolchain)", "root_out_dir") + "/iossim",
     ]
   }
 }