fix(timeout): defer error creation until timeout occurs (ReactiveX#5497)

- closes ReactiveX#5491

src/internal/operators/timeout.ts

@@ -7,6 +7,9 @@ import { TimeoutError } from '../util/TimeoutError';
 import { MonoTypeOperatorFunction, SchedulerAction, SchedulerLike, TeardownLogic } from '../types';
 import { timeoutWith } from './timeoutWith';
 import { throwError } from '../observable/throwError';
+import { defer } from '../observable/defer';
+
+function timeoutErrFactory() { return throwError(new TimeoutError()); }
 
 /**
  *
@@ -88,5 +91,5 @@ import { throwError } from '../observable/throwError';
  */
 export function timeout<T>(due: number | Date,
                            scheduler: SchedulerLike = async): MonoTypeOperatorFunction<T> {
-  return timeoutWith(due, throwError(new TimeoutError()), scheduler);
+  return timeoutWith(due, defer(timeoutErrFactory), scheduler);
 }