adds these new special languages as constants. Currently LANGUAGE_NONE (to be renamed in that issue to LANGUAGE_NOT_SPECIFIED) is allowed to be assigned to some things, like nodes and path aliases, however, these languages are added on as extra items to the language list in form functions.
We should let users assign LANGUAGE_NOT_APPLICABLE and LANGUAGE_MULTIPLE as well to things like files, nodes, etc. Since the list of special languages grows in Drupal 8 from 1 (in Drupal 7) to 4 with these additions (and the already present LANGUAGE_SYSTEM), we either want to have a common language list extension wrapper or add these languages as regular pieces in the language table and then figure out. Both have disadvantages. If we extend the list occasionally in code, we need to remember to do it at all times when applied to the same thing (such as for nodes in the filter UI and the node forms). If we decide to add them as languages in the language table, then we'll need to filter that down when needed, such as when UI language is considered, where these special languages have no meaning (except LANGUAGE_SYSTEM).
BTW solvingwould have other benefits too, eg. you could configure you don't want certain special languages to show up for nodes or files and always enforce an exact language selection, etc.
Currently both LANGUAGE_NONE and LANGUAGE_SYSTEM are added occasionally when needed to the language list.
Marking postponed onlanding.
FAILED: [[SimpleTest]]: [MySQL] Unable to apply patch 1471432-116.patch. Unable to apply patch. See the log in the details link for more information.
PASSED: [[SimpleTest]]: [MySQL] 36,891 pass(es).
PASSED: [[SimpleTest]]: [MySQL] 36,890 pass(es).