Issue #2051467 by jhedstrom, dawehner, amateescu, Berdir, herom, Mile23: Expand and convert to phpunit tests for \Drupal\Component\Transliteration

Issue #2339151 by EclipseGc, tim.plunkett, Gábor Hojtsy, effulgentsia: Conditions / context system does not allow for multiple configurable contexts, eg. language types

Issue #2246647 by mpdonadio, cilefen, YesCT, tim.plunkett: Rename PluginBag to LazyPluginCollection.