upgrade dependencies, including migration to package:test

upgrade dependencies, including migration to package:test
dart_style becomes a dev_dependency, and remove the ability to auto-run it from dart backend, instead use the test formatter
migrate to package:test, which has a few tricky bits:
* expect can only appear inside a test now (https://github.com/dart-lang/test/issues/132)
* mirrors is needed to get the test folder (https://github.com/dart-lang/test/issues/110)
* test `main` can't take arguments. not sure what's up there, but not a big deal for us either.

R=vsm@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/04e9e762c1f44dda074ce211335d81892c8852e5

[Jennifer Messerly, 2015-06-01 21:10:56]

jmesserly@google.com changed reviewers:
+ vsm@google.com

[Jennifer Messerly, 2015-06-01 21:10:56]

I'll push a branch too so we can get travis results

[Jennifer Messerly, 2015-06-01 21:11:22]

On 2015/06/01 21:10:56, John Messerly wrote:
> I'll push a branch too so we can get travis results

https://github.com/dart-lang/dev_compiler/tree/deps

[Jennifer Messerly, 2015-06-01 21:19:06]

Passed https://travis-ci.org/dart-lang/dev_compiler/builds/64984494

[vsm, 2015-06-01 21:50:10]

lgtm!

[Jennifer Messerly, 2015-06-01 21:54:17]

Committed patchset #1 (id:1) manually as
04e9e762c1f44dda074ce211335d81892c8852e5 (presubmit successful).