Try to unbreak gyp build-only bots after https://codereview.chromium.org/1918143004/

build/gn_migration.gypi

Index: build/gn_migration.gypi
diff --git a/build/gn_migration.gypi b/build/gn_migration.gypi
index 4462023daeb42b3b158310d5696094ef6cf6b0a2..f1aa2223c89c798f28d30b966555c54816b01417 100644
--- a/build/gn_migration.gypi
+++ b/build/gn_migration.gypi
@@ -642,6 +642,15 @@
                 '../ui/touch_selection/ui_touch_selection.gyp:ui_touch_selection_unittests_run',
               ],
             }],
+            ['OS!="android" and OS!="ios" and chromecast==0', {

[Ken Rockot(use gerrit already), 2016/04/29 15:36:45]

hmm - i thought we were running all of these on android

[Nico, 2016/04/29 15:39:04]

\noideanico. I chose this conditional because build/all.gyp depends on
services/shell/shell.gyp with this conditional. What should the conditional be
then? Just drop the OS!=android bit?

+              'dependencies': [
+                '../ipx/mojo/ipc_mojo.gyp:ipc_mojo_unittests_run',

[Ken Rockot(use gerrit already), 2016/04/29 15:36:45]

s/ipx/ipc/

[Nico, 2016/04/29 15:39:04]

Done.

+                '../mojo/mojo_edk_tests.gyp:mojo_js_unittests_run',
+                '../mojo/mojo_edk_tests.gyp:mojo_js_integration_tests_run',
+                '../mojo/mojo_edk_tests.gyp:mojo_system_unittests_run',
+                '../services/shell/shell.gyp:mojo_shell_unittests_run',
+              ],
+            }],
             ['use_ash==1', {
               'dependencies': [
                 '../ash/ash.gyp:ash_unittests_run',