Also, add tests to verify that our coverage is actually being tested!

https://github.com/flutter/flutter/issues/10688

https://github.com/flutter/flutter/issues/10688

* Bump to Dart SDK 1.24.0-dev.6.7.

* nits and fixes

VERSION: 0.0.7-dev
flutter: 0.0.27-dev
flutter_driver: 0.0.5-dev
flutter_test: 0.0.5-dev

VERSION: 0.0.6
flutter: 0.0.26
flutter_driver: 0.0.4
flutter_test: 0.0.4

* Rev versions for alpha branch

* Rev versions after alpha

And add a script to rev the versions.

* Bump to test `0.12.20`.

Some test `0.12.20` highlights:
  * introduces `expectLater()`  that returns a `Future` that completes when the matcher has finished running
  * deprecates the `verbose` parameter to `expect()` and the `formatFailure()` (to be removed in `0.13.0`)

Otherwise:
  * to keep up w/ the deprecation of `verbose`, removes `widget_tester` API to pass `verbose` flag (alternatively we could suppress the warning for now)

* Update stack manipulation.

* Fix framecount.

* ups pinned `test` to `0.12.15+9` (to play nice w/ the latest analyzer)
* integrates `analyzer` with analysis driver defaulting to ON

* Remove the workaround that pinned args to v0.13.6
This reverts most of the changes in commit 6331b6c8
* throw exception if exit code is not an integer
* rework command infrastructure to throw ToolExit when non-zero exitCode
* convert commands to return Future<Null>
* cleanup remaining commands to use throwToolExit for non-zero exit code
* remove isUnusual exception message
* add type annotations for updated args package

Switch our pubspec.yamls to using SDK sources so that we can have consistent
source types when we depend on these packages from external packages using SDK
sources.

* suppress warning; decouple the analyzer versions

* also pass in --no-packages-dir

* Update tools to use `analyzer` from vended Dart SDK.

* updates `flutter_tools` and `flutter_test` to use the SDK-vended `analyzer` package
* tweaks dependency tracking logic to only record the SDK-vended `analyzer` so as not to crash on spurious conflicts (due to transitive dependencies)

* Review fixes.

* Udpate to Dart `1.20.0-dev.1.0`.

Udpate to Dart `1.20.0-dev.1.0` and corresponding `analyzer` package.

* Added `--no-packages-dir`.

* Revert extension to master.

* Added ignores.

* Review nits.

* More nits.

Last dev push for `1.18`.