unittest: refactor ahead of matcher changes

CHANGELOG.md

+##0.12.0
+
+* Removed `FailureHandler`, `DefaultFailureHandler`,
+`configureExpectFailureHandler`, and `getOrCreateExpectFailureHandler`. These

[nweiz, 2015/01/26 22:44:09]

Indent +2 here and below.

[kevmoo, 2015/01/27 00:11:29]

Done.

+are no longer needed.

[nweiz, 2015/01/26 22:44:09]

Explain why they're no longer needed. Imagine you're talking to a user who was
using them previously.

[kevmoo, 2015/01/27 00:11:29]

Done.

+
+* Moved a number of APIs from `matcher`, including:

[nweiz, 2015/01/26 22:44:09]

"from `matcher`" -> "from `matcher` into `unittest`"

Remove ":"

[kevmoo, 2015/01/27 00:11:29]

Done.

+`completes`, `completion`,`ErrorFormatter`,`expect`,`fail`,`prints`,

[nweiz, 2015/01/26 22:44:09]

Add spaces after commas.

[kevmoo, 2015/01/27 00:11:29]

Done.

+`TestFailure`,`Throws`, and all of the `throws` methods.
+
+    * `expect` no longer has a named `FailureHandler` argument.
+
+    * `expect` added an optional `ErrorFormatter` argument.

[nweiz, 2015/01/26 22:44:09]

Including the name of the argument will be more useful than the type name.

[kevmoo, 2015/01/27 00:11:29]

Done.

+
+* Removed several members from `SimpleConfiguration` that relied on removed
+  functionality: `onExpectFailure`, `onTestResult`, and
+  `stopTestOnExpectFailure`.
+
 ##0.11.5
 
 * Bumped the version constraint for `matcher`.
 
 ##0.11.4
 
 * Bump the version constraint for `matcher`.
 
 ##0.11.3
 
@@ skipping 87 matching lines @@
 * **NEW!** `expectAsyncUntil` replaces the now deprecated `expectAsyncUntil0`,
     `expectAsyncUntil1` and `expectAsyncUntil2`
 * `TestCase`:
     * Removed properties: `setUp`, `tearDown`, `testFunction`
     * `enabled` is now get-only
     * Removed methods: `pass`, `fail`, `error`
 * `interactive_html_config.dart` has been removed.
 * `runTests`, `tearDown`, `setUp`, `test`, `group`, `solo_test`, and
   `solo_group` now throw a `StateError` if called while tests are running.
 * `rerunTests` has been removed.