The way we pick observatory port # has changed and we have broken
logic that handles port 8181. To fix the buildbot, switch to port
8182. We can later figure out what we want to do when we clean up
port handling.
The old VM extention for extracting the timeline data is gone.
Switch to the new '_getVMTimeline' API.
Runs a test app and a driver test simultaneously, then stops the app.
Usage:
```
flutter drive --target=/path/to/test/app.dart
```
This command will look for `/path/to/test/app_test.dart` by
convention. We will expand into other ways of discovering tests in the
future.
This commit contains:
- FlutterDriver API for e2e tests usable in conjunction with package:test
- FlutterDriverExtension to be enabled by the application in order to
allow an external agent to connect to it and drive user interactions and
probe into the element tree
- initial implementations of tap, findByValueKey and getText commands (to
be expanded in future PRs)