Simple multi-url support for mojo apps

mojo/tools/data/apptests

 # This file contains a list of Mojo gtest unit tests.
 # This must be valid python. It can use the |config| global that will be a
 # mopy.config.Config object and must set a |tests| global that will contain the
 # tests to run.
 # TODO(vtl|msw): Add a way of specifying data dependencies.
 
 tests = [
   {
     "test": "mojo:clipboard_apptests",
   },
@@ skipping 61 matching lines @@
     },
     {
       "test": "mojo:js_apptests",
     },
     {
       "test": "mojo:reaper_apptests",
     },
     {
       "test": "mojo:dart_apptests",
     },
+    {
+      "test": "mojo:shell_apptests",
+    },
   ]