Remove solo_group accidentally left in test.
Remove solo_group accidentally left in test.

DrMarcII/webdriver.dart,bwu-dart-contributing/webdriver.dart,DrMarcII/webdriver.dart,google/webdriver.dart,staats-google/webdriver.dart,bwu-dart-contributing/webdriver.dart,bwu-dart-contributing/webdriver.dart,staats-google/webdriver.dart,DrMarcII/webdriver.dart,DrMarcII/webdriver.dart,google/webdriver.dart,staats-google/webdriver.dart,google/webdriver.dart,bwu-dart-contributing/webdriver.dart,staats-google/webdriver.dart