Enables ASAN build and test for Dart

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 58 matching lines @@
         "--url-mappings=mojo:example_service=test:example_service"
       ],
       "launched-services": ["test:example_service"],
     },
     {
       "test": "mojo:js_apptests",
     },
     {
       "test": "mojo:reaper_apptests",
     },
-  ]
-
-# TODO: get dart unittests working with asan.
-if not config.sanitizer:
-  tests += [
     {
       "test": "mojo:dart_apptests",
     },
   ]