Make tests pass on master

Tests currently [fail on master](https://travis-ci.org/angular/angular.dart/jobs/26680839) with:

```
Chrome 35.0.1916 (Linux) annotations component should set all fields on clone when all the fields are set FAILED
	Test failed: Caught Unsupported operation: Can't use '_applyAuthorStyles' in reflection because it is not included in a @MirrorsUsed annotation.
```

I believe with is linked with guinness now using `Mirrors`.

Commit details:
1. some refactoring in _specs.dart,
2. remove tests that belong to guinness, I'll make sure they are in the guinness lib,
3. fix tests by running them only in Dart. I'm not sure if this is a proper fix ? I'll try ro investigate

/cc @vsavkin