Bump version to 8.0.2. (dart-lang#3596)

* Remove Class assert for ClassTypedef.

* Bump to 8.0.2.

Bump version to 8.0.1. (dart-lang#3592)

Bump version to 8.0.0 (dart-lang#3583)

* Bump version to 7.0.3 (really)

* Change to 8.0.0

Prepare for dartdoc 6.3.0. (dart-lang#3430)

* Update changelog and pubspec for dartdoc 6.3.0.

* Missed a crucial change in the changelog

Prepare for dartdoc 6.2.2 (dart-lang#3402)