Update angular_compiler CHANGELOG in preparation for 0.4.0 final release.
Update angular_compiler CHANGELOG in preparation for 0.4.0 final release.

PiperOrigin-RevId: 207623209

angulardart/angular,chalin/angular2,chalin/angular2,angulardart/angular,matanlurey/angular,angulardart/angular,matanlurey/angular,chalin/angular2,matanlurey/angular