Type cast should try to remove readonly modifier

The compiler should try to use mutable versions of readonly tuples when couldn't cast readonly tuples to mutable arrays mainly for usability of as const. The performance impact of this would be a little because the condition when this check runs is limited.

TypeScript Version: 3.7.x-dev.20200123

Search Terms:

Code

([0] as [0]) as number[];
([0] as [0]) as readonly number[];
// As the expansion of [0] as const
([0] as readonly [0]) as number[]; // error
([0] as readonly [0]) as readonly number[];

Expected behavior:
pass
Actual behavior:

Conversion of type 'readonly [0]' to type 'number[]' may be a mistake because neither type sufficiently overlaps with the other. If this was intentional, convert the expression to 'unknown' first.
  The type 'readonly [0]' is 'readonly' and cannot be assigned to the mutable type 'number[]'.(2352)

Playground Link: http://www.typescriptlang.org/play/index.html?target=99&ts=3.8.0-dev.20200123&ssl=1&ssc=1&pln=6&pc=1#code/BQbQDAugBAhgzlcECUsEDsCuBbARgUwCcQIBuAKFEjUUlXikPxgBMB7dAGwE8os8iJCgHphUAIIIALgAt8UfAA8ADjHRwAlhyhsAZrWgMAxhzhTKSGk1YceB+hhwFiZKKIWFCbQheoNr7Fy8SA6MzIF2-M5C5EA

Related Issues:

Empieza reproduciendo los ejemplos de cast de tuplas readonly en el TypeScript Playground o con TypeScript 3.7.x-dev.20200123; después, sigue las comprobaciones del compilador de insufficient-overlap y de asignabilidad de readonly. Se considera terminado cuando el cast de la tupla readonly a number[] pasa como se espera sin requerir un cast intermedio a unknown, mientras las comprobaciones de seguridad existentes permanecen intactas.