Closes #6

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//1027193004

See #6

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//1004013002

See #6

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//1008483003

Closes #5

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//983573002

This uses the right executables on OS X and Windows, and passes flags
to disable even more features.

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//978093003

See #5

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//979513002

This moves some files into lib/src/runner/vm to match
lib/src/runner/browser, and moves the test into a directory structure
matching that of lib/src/.

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//979523002

See #5

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//971103002

This is necessary to avoid an IO dependency in lib/unittest.dart, which would
prevent browser tests from running.

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//971123002

See #19

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//961003005

See #5

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//959383004

See #5

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//958423002

This will allow the test runner to compile test files to JavaScript.
It runs dart2js instances in parallel but prints their output
sequentially.

See #5

R=rnystrom@google.com, kevmoo@google.com

Review URL: https://codereview.chromium.org//960723002

See #5

R=rnystrom@google.com, kevmoo@google.com

Review URL: https://codereview.chromium.org//958753002

This creates the following four subdirectories:

* `frontend/`, which is for user-visible libraries exported by
  `lib/unittest.dart`.

* `backend/`, which is for libraries that define the internal
  structure of test suites and how they're run in a platform-
  independent manner.

* `runner/`, which is for libraries that are specifically useful for
  the test runner. This includes code that deals with multiple test
  suites at once as well as platform-specific test running code.

* `util/`, which contains various utility libraries that aren't
  specific to unittest's use-case. Individual utility functions can
  still go in `lib/util.dart`.

* `deprecated/`, which contains deprecated libraries.

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//955543002