Add GN conversions for more GYP flags

build/toolchain/mac/BUILD.gn

 # 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.
 
 # Should only be running on Mac.
-assert(is_mac)
+assert(is_mac || is_ios)
 
 cc = rebase_path("//third_party/llvm-build/Release+Asserts/bin/clang", ".", root_build_dir)
 cxx = rebase_path("//third_party/llvm-build/Release+Asserts/bin/clang++", ".", root_build_dir)
 ld = cxx
 
 # This will copy the gyp-mac-tool to the build directory. We pass in the source
 # file of the win tool.
 gyp_mac_tool_source =
   rebase_path("//tools/gyp/pylib/gyp/mac_tool.py", ".", root_build_dir)
 exec_script("setup_toolchain.py", [ gyp_mac_tool_source ], "value")
@@ skipping 56 matching lines @@
   #}
   tool("stamp") {
     command = "\${postbuilds}touch \$out"
     description = "STAMP \$out"
   }
   tool("copy") {
     command = "ln -f \$in \$out 2>/dev/null || (rm -rf \$out && cp -af \$in \$out)"
     description = "COPY \$in \$out"
   }
 }