multi calls for democracy.votes and staking.controllers (#887)

* .multi for democracy.votes & stating.controllers

* Removed leftover comment from https://github.com/polkadot-js/api/pull/875

* no new line at the end

packages/api-derive/src/balances/fees.ts

@@ -12,7 +12,6 @@ import { drr } from '../util/drr';
 
 export function fees (api: ApiInterface$Rx) {
   return (): Observable<DerivedFees> => {
-    // FIXME Remove fees checks, only use balances (fees is a removed module now)
     return (combineLatest([
       api.query.balances.creationFee(),
       api.query.balances.existentialDeposit(),

packages/api-derive/src/democracy/votes.ts

@@ -14,10 +14,7 @@ export function votes (api: ApiInterface$Rx) {
     return !accountIds || !accountIds.length
       ? of([]).pipe(drr())
       : combineLatest(
-        // FIXME Convert to multi
-        accountIds.map(
-          (accountId) => api.query.democracy.voteOf([referendumId, accountId]) as Observable<Vote>
-        )
+        api.query.democracy.voteOf.multi(accountIds.map(accountId => [referendumId, accountId])) as Observable<Vote>
       ).pipe(
         drr()
       );

packages/api-derive/src/staking/controllers.ts

@@ -11,10 +11,7 @@ import { drr } from '../util/drr';
 
 function allBonds (api: ApiInterface$Rx, stashIds: Array<AccountId>) {
   return combineLatest(
-    // FIXME Convert to multi
-    stashIds.map((id) =>
-      (api.query.staking.bonded(id) as Observable<Option<AccountId>>)
-    )
+    api.query.staking.bonded.multi(stashIds) as Observable<Option<AccountId>>
   );
 }