Remove unnnecessary `show Future` from `dart:async` imports.
Based on https://github.com/dart-lang/isolate/pull/41
diff --git a/example/runner_pool.dart b/example/runner_pool.dart
index b479a60..1c36b84 100644
--- a/example/runner_pool.dart
+++ b/example/runner_pool.dart
@@ -4,8 +4,6 @@
library isolate.example.runner_pool;
-import 'dart:async' show Future;
-
import 'package:isolate/isolate_runner.dart';
import 'package:isolate/load_balancer.dart';
diff --git a/lib/load_balancer.dart b/lib/load_balancer.dart
index a04ab9c..97d7cad 100644
--- a/lib/load_balancer.dart
+++ b/lib/load_balancer.dart
@@ -5,7 +5,7 @@
/// A load-balancing runner pool.
library isolate.load_balancer;
-import 'dart:async' show Completer, Future, FutureOr;
+import 'dart:async' show Completer, FutureOr;
import 'runner.dart';
import 'src/errors.dart';
diff --git a/lib/registry.dart b/lib/registry.dart
index c17f327..d972e09 100644
--- a/lib/registry.dart
+++ b/lib/registry.dart
@@ -5,7 +5,7 @@
/// An isolate-compatible object registry and lookup service.
library isolate.registry;
-import 'dart:async' show Future, Completer, TimeoutException;
+import 'dart:async' show Completer, TimeoutException;
import 'dart:collection' show HashMap, HashSet;
import 'dart:isolate' show RawReceivePort, SendPort, Capability;
diff --git a/lib/runner.dart b/lib/runner.dart
index 5d31194..c902f86 100644
--- a/lib/runner.dart
+++ b/lib/runner.dart
@@ -6,7 +6,7 @@
/// or even isolate.
library isolate.runner;
-import 'dart:async' show Future, FutureOr;
+import 'dart:async' show FutureOr;
/// Calls a function with an argument.
///
