`adb` can sometimes hang, which will in turn hang the Dart isolate if
we're using `Process.runSync()`. This changes many of the `Device` methods
to return `Future<T>` in order to allow them to use the async process
methods. A future change will add timeouts to the associated calls so
that we can properly alert the user to the hung `adb` process.
This is work towards #7102, #9567
* Fix tests to use Ahem, and helpful changes around that
- Fix fonts that had metric-specific behaviours.
- LiveTestWidgetsFlutterBinding.allowAllFrames has been renamed
to LiveTestWidgetsFlutterBinding.framePolicy.
- LiveTestWidgetsFlutterBinding now defaults to using a frame policy
that pumps slightly more frames, to animate the pointer crosshairs.
- Added "flutter run --use-test-fonts" to enable Ahem on devices.
- Changed how idle() works to be more effective in live mode.
- Display the test name in live mode (unless ahem fonts are enabled).
- Added a toString to TextSelectionPoint.
- Style nit fixes.
* Roll engine to get Ahem changes.
* Update tests for dartdoc changes.
* Fix flutter_tools tests
Function keys don't work great on any platform we support:
* Mac doesn't have first-class function keys.
* On Ubuntu: F1 opens the system help and F10 opens the file dialog.
* ... and Windows is a mess as well.
