Expose MGL interface through NaCl IRT

mojo/public/platform/native/BUILD.gn

 # Copyright 2014 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.
 
-assert(!defined(is_nacl) || !is_nacl)
-
 import("../../mojo_sdk.gni")
 
 mojo_sdk_source_set("system") {
   sources = [
     "system_thunks.c",
     "system_thunks.h",
   ]
   defines = [ "MOJO_SYSTEM_IMPLEMENTATION" ]
   mojo_sdk_deps = [ "mojo/public/c/system" ]
 
@@ skipping 105 matching lines @@
 }
 
 mojo_sdk_source_set("mgl_onscreen_thunks") {
   sources = [
     "mgl_onscreen_thunks.c",
     "mgl_onscreen_thunks.h",
   ]
 
   mojo_sdk_deps = [ "mojo/public/c/gpu:MGL_onscreen" ]
 }