Expando properties with `isolatedDeclarations`

[exuanbo]

export interface Type<T> {
  __brand: T;
}

export function makeType<T>(): Type<T> {
  return {} as Type<T>;
}

export function fn(): void {}

export declare namespace fn {
  export var type: Type<string>;
}

fn.type = makeType();

https://www.typescriptlang.org/play/?isolatedDeclarations=true#code/KYDwDg9gTgLgBASwHY2FAZgQwMbDgFQE8xgAefAPjgG8AoOOAfUYCMpMkATALgIG5aAX1q1QkWHHQBXJNhgIISOAFtMAa2BES5CgAoAlLy1lKNenCjAYUqEuqC4mAM4FiJigOGjw0eNNnyipJIBrwAbhAInDReYr5wnMDYADaYlnBImMrATmA4eOh25nESYWlwMG5GbqROMFDIAOYeQiKFAHSVJHAAvCrqmm4GAkA

This code has no issue with isolatedDeclarations, but is reported as slow types by JSR.

isolatedDeclarations requires manually declaring ambient namespace for the expando properties, so ideally no transformation is needed.

Affected: https://github.com/exuanbo/di-wise/blob/bd9580220a6d33bc4ca917825166713106252736/src/token.ts#L28-L34