Support Android and iOS platforms

Is there a current method to run tests in a mobile browser or plans to do so in the future?

For example: `pub run test -p android` runs dart tests in a usb connected android device and results show in the commandline.

Start by checking the current `pub run test` platform support and how tests are expected to run in a mobile browser. Compare the requested Android example with the desired iOS behavior; done would require a defined, working way to run Dart tests on both platforms and report results in the command line.

Written by the indexing model from the issue text.