Convert Mojo tests to use swarming.

testing/test.gni

 # 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.
 
 # ==============================================================================
 # TEST SETUP
 # ==============================================================================
 
 template("_gen_isolate") {
   testonly = true
@@ skipping 320 matching lines @@
     }
 
     # TODO(GYP): Delete this after we've converted everything to GN.
     # The _run targets exist only for compatibility with GYP.
     group("${target_name}_run") {
       testonly = true
       deps = [
         ":${invoker.target_name}",
       ]
     }
+
+    if (defined(invoker.output_name) && target_name != invoker.output_name) {
+      group("${invoker.output_name}_run") {
+        testonly = true
+        deps = [
+          ":${invoker.target_name}",
+        ]
+      }
+    }
   }
 }