Enhance the Dart unittest library to support multiple invocations in the same application run.

I am creating e2e tests for dart on App Engine and want to avoid redeploying the app each time I need to run a specific set of tests. Instead I have enhanced the unittest library with a method which creates a new "global" test environment which can be used for this specific run of tests.
Before I had to redeploy the app each time (takes ~2-4mins) to get a fresh test environment.

BUG=
R=kevmoo@google.com, kustermann@google.com

Review URL: https://codereview.chromium.org//709903004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41741 260f80e4-7a28-3924-810f-c04153c831b5
Remove unused fields in analyzer.

R=brianwilkerson@google.com
BUG=

Review URL: https://codereview.chromium.org//727763003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41742 260f80e4-7a28-3924-810f-c04153c831b5
Remove unused fields from analysis_server.

R=brianwilkerson@google.com, paulberry@google.com
BUG=

Review URL: https://codereview.chromium.org//725153002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41743 260f80e4-7a28-3924-810f-c04153c831b5
Code clean-up and minor bug fix

R=scheglov@google.com

Review URL: https://codereview.chromium.org//730533003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41744 260f80e4-7a28-3924-810f-c04153c831b5