case CONCURRENT_MODE_SYMBOL_STRING:
          case DEPRECATED_ASYNC_MODE_SYMBOL_STRING:
            return ElementTypeOtherOrUnknown;
          case PROVIDER_NUMBER:
          case PROVIDER_SYMBOL_STRING:
            return ElementTypeContext;
          case CONTEXT_NUMBER:
          case CONTEXT_SYMBOL_STRING:
            return ElementTypeContext;
          case STRICT_MODE_NUMBER:
          case STRICT_MODE_SYMBOL_STRING:
            return ElementTypeOtherOrUnknown;
          case PROFILER_NUMBER:
          case PROFILER_SYMBOL_STRING:
            return ElementTypeProfiler;
          default:
            return ElementTypeOtherOrUnknown;
        }
    }
  }
   This is a slightly annoying indirection.
   It is currently necessary because DevTools wants to use unique objects as keys for instances.
   However fibers have two versions.
   We use this set to remember first encountered fiber for each conceptual instance.
  function getPrimaryFiber(fiber: Fiber): Fiber {
    if (primaryFibers.has(fiber)) {
      return fiber;
    }
    const {alternate} = fiber;
    if (alternate != null && primaryFibers.has(alternate)) {