Restore gn_all to gn_isolate_map.pyl, unbreak ios builders

testing/buildbot/gn_isolate_map.pyl

 ## Copyright 2015 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.
 
 # gn_isolate_map.pyl - A mapping of Ninja build target names to GN labels and
 # test type classifications for the tests that are run on the bots.
 #
 # This mapping is used by MB so that we can uniformly refer to test binaries
 # by their Ninja target names in the recipes and not need to worry about how
 # they are referred to in GN or GYP specifically (the GYP target name is pretty
@@ skipping 444 matching lines @@
   "gl_tests": {
     "label": "//gpu:gl_tests",
     "type": "raw",
     "args": [],
   },
   "gl_unittests": {
     "label": "//ui/gl:gl_unittests",
     "type": "raw",
     "args": [],
   },
+  "gn_all": {
+    "label": "//:gn_all",
+    "type": "additional_compile_target",
+  },
   "gn_unittests": {
     "label": "//tools/gn:gn_unittests",
     "type": "raw",
     "args": [],
   },
   "google_apis_unittests": {
     "label": "//google_apis:google_apis_unittests",
     "type": "console_test_launcher",
   },
   "gpu_ipc_service_unittests": {
@@ skipping 475 matching lines @@
   },
   "wtf_unittests": {
     "label": "//third_party/WebKit/Source/wtf:wtf_unittests",
     "type": "console_test_launcher",
   },
   "xmllite_xmpp_unittests": {
     "label": "//webrtc:xmllite_xmpp_unittests",
     "type": "console_test_launcher",
   }
 }