rev to analyzer 0.30.0

fix a few analysis warnings

Fixes https://github.com/dart-lang/test/issues/594

Runs the following tests:

- dartanalyzer
- dartfmt
- vm tests excluding all browser tags
- dartium tests

Note that the dev SDK appears to leave pub running after a successful run of tests. This will need to be investigated further.

Adding hooks for new reporters and test platforms. These hooks are not intended to be a part of the external API and thus are aptly documented.

* plumb chain-stack-traces configuration through

* correctly plumb new flag through and add corresponding tests

* add example command

* chains -> chained

Dartfmt *.dart

* correctly kill Dartium on Linux

* adding try catch

* fix style

It’s not needed at runtime.
Allows us to keep pkg/js as a dev dependency and keep DDC happy

Fixes https://github.com/dart-lang/test/issues/567

Hoping to get the bots to a semi-sane spot

BUG=
R=kevmoo@google.com

Review-Url: https://codereview.chromium.org//2745253004 .

Closes #555

BUG=
R=nweiz@google.com

Review-Url: https://codereview.chromium.org//2740003005 .

Closes #554

We're using a feature that was introduced in
1.6.0 (Disconnector.disconnect's return value).

Closes #556