…ass extending a d.ts class (#2537) * add test * improve test * add comment * new variant method for DTS * fix issue * typo and small adjustment * refactor to deal with some exceptions * add symbols dispose and asyncDispose * support some text region support in d.ts files * refactor to avoid inconsistencies * special check regarding computed property names * also check fields, getters, setters * small refactoring
395f11c