Mojo: Run mojo_shell_tests on trybots on all platforms.

R=sky@chromium.org

Review URL: https://codereview.chromium.org/414143002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285474 0039d316-1c4b-4281-b951-d872f2087c98

testing/buildbot/chromium_trybot.json

@@ -96,6 +96,7 @@
     "mojo_public_system_unittests",
     "mojo_public_utility_unittests",
     "mojo_service_manager_unittests",
+    "mojo_shell_tests",
     "mojo_system_unittests",
     {
       "test": "nacl_loader_unittests",
@@ -160,10 +161,6 @@
       "test": "aura_unittests",
       "platforms": ["linux", "win"]
     },
-    {
-      "test": "mojo_shell_tests",
-      "platforms": ["linux"]
-    },
     {
       "test": "mojo_view_manager_unittests",
       "platforms": ["linux", "win"]