Make *some* version of the Mac GN build work.

mojo/services/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.
 
 import("//build/config/ui.gni")
 
 group("services") {
   deps = [
     "//mojo/services/public/interfaces/clipboard",
     "//mojo/services/public/interfaces/content_handler",
     "//mojo/services/public/interfaces/geometry",
     "//mojo/services/public/interfaces/input_events",
     "//mojo/services/public/interfaces/native_viewport",
     "//mojo/services/public/interfaces/navigation",
     "//mojo/services/public/interfaces/network",
     "//mojo/services/public/interfaces/surfaces",
     "//mojo/services/public/interfaces/view_manager",
   ]
 
   if (!is_component_build) {
     deps += [
       "//mojo/services/html_viewer",
       "//mojo/services/network",
     ]
+  
+    # TODO(GYP): Make this work.
+    if (is_mac) {
+      deps -= [
+        "//mojo/services/html_viewer",
+      ]
+    }
   }
 }