Replace fraction stuffs with Permill and Perbill about darwinia HOT 1 CLOSED

const ACCURACY: u128 = u32::max_value() as ExtendedBalance + 1;

	// TODO: ready for hacking
	// power is a mixture of ring and kton
	fn slashable_balance_of(stash: &T::AccountId) -> ExtendedBalance {
		Self::bonded(stash)
			.and_then(Self::ledger)
			.map(|l| {
				l.active_ring.saturated_into::<ExtendedBalance>()
					+ l.active_kton.saturated_into::<ExtendedBalance>() * Self::kton_vote_weight() / ACCURACY
			})
			.unwrap_or_default()
	}

	// total_kton * kton_vote_weight / ACCURACY = total_ring
	// it ensures that when rewarding validators
	// reward to ring_pool will be the same with the
	// reward to kton_pool
	// that means 50% reward is distributed to ring holders,
	// another 50% reward is distributed to kton holders
	fn kton_vote_weight() -> ExtendedBalance {
		let total_ring = Self::ring_pool().saturated_into::<ExtendedBalance>();
		// to avoid 'attempt to divide by zero'
		let total_kton = Self::kton_pool().saturated_into::<ExtendedBalance>().max(1);
		// total_ring and total_kton are within the scope of u64
		// so it is safe to multiply ACCURACY when extended to u128
		total_ring * ACCURACY / total_kton
	}