Make test iframes visible when debugging.

Closes #429

Closes #485

R=nweiz@google.com
BUG=

Review URL: https://codereview.chromium.org//2392743005 .

This reverts commit 4ca058ce.

Closes #477

This will be useful for Bolt, which has out-of-band information about
what platforms each given test is intended to run on.

Don't capture stack traces by default.

Stack traces are now only captured for the JSON reporter. Capturing
traces was slow enough to be a serious problem for test suites with many
tests.

Closes #457

This introduces a zone-scoped `Configuration.current`. This makes it
much easier to propagate the configuration everywhere it needs to go,
especially to plugins.

Now that https://codereview.chromium.org/1241723003/ has landed

R=keertip@google.com

Review URL: https://codereview.chromium.org//2379083002 .

It was printing the wrong number of seconds for durations longer than a
minute.

Closes #463

Closes #461

R=nweiz@google.com

Review URL: https://codereview.chromium.org//2285133005 .

There is still a warning before of 'expectAsync', but this would
require making it generic, which is outside of the scope of this CL.

R=brianwilkerson@google.com, rnystrom@google.com, nweiz@google.com
BUG=

Review URL: https://codereview.chromium.org//2282003002 .

The Dartium versions that didn't support this are long since out of
circulation.

R=jakemac@google.com

Review URL: https://codereview.chromium.org//2272223003 .

Closes #453

R=devoncarew@google.com

Review URL: https://codereview.chromium.org//2271383002 .

This isn't used by test proper, but it's needed by some
Google-internal code.

R=jmesserly@google.com

Review URL: https://codereview.chromium.org//2269403002 .

Updates `test` to be constraint-compatible with the latest analyzer (0.28.0-alpha.1).

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

Review URL: https://codereview.chromium.org//2255083003 .

R=jakemac@google.com

Review URL: https://codereview.chromium.org//2232533002 .

Closes #327

R=leafp@google.com

Review URL: https://codereview.chromium.org//2184543002 .

BUG=https://github.com/dart-lang/test/issues/442
R=kevmoo@google.com

Review URL: https://codereview.chromium.org//2124983005 .

Closes #393

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//2099553002 .

Closes #394

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//2123353002 .

This moves the responsibility for printing skip messages to the engine,
rather than the reporter. Reporters now just need to choose how to
display the messages produced by the engine.

This lays the groundwork for #394, since skip messages can now be
emitted during the run of a test.

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//2091173002 .

This makes it possible for a test to be marked skip based on its runtime
behavior rather than being strictly based on its metadata.

See #393 and #394

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//2099503002 .

Hide strong-mode warnings in test directory
Remove unused imports and fields
Consolidate line splitter instances

R=nweiz@google.com

Review URL: https://codereview.chromium.org//2068363002 .

The new constraint reflects the actual APIs we're using.

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//2087003004 .

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//2086743002 .

Closes #420

Review URL: https://codereview.chromium.org//2066113002 .

This version hasn't been released yet.

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

Review URL: https://codereview.chromium.org//2048773002 .

This output was added in a recent dart2js version, and it's redundant
with test's own output. It's also breaking tests.

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

Review URL: https://codereview.chromium.org//2044263002 .

R=cbracken@google.com

Review URL: https://codereview.chromium.org//2042403003 .

This is useful internally for Google, and is not considered a public
feature with stability guarantees.

Currently this doesn't support --pub-serve mode. If that becomes
necessary, it can be added later.

R=cbracken@google.com

Review URL: https://codereview.chromium.org//2040883003 .

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//2039413002 .

These are only intended to be used by Google's internal test runner.
Their API is not public nor is it guaranteed to be stable. They're being
moved into the external repository to ease the pain of merging.

R=cbracken@google.com

Review URL: https://codereview.chromium.org//2009163003 .