docs(API): 翻译完了 test/async

aio/content/translations/cn/api-plan.md

@@ -96,10 +96,9 @@
 [x]  | forms/NgSelectOption  | 0.17
 [x]  | common/PercentPipe  | 0.17
 [x]  | forms/ValidatorFn  | 0.17
-[ ]  | http/RequestOptionsArgs  | 0.17
 [ ]  | animations/animation  | 0.17
 [x]  | common/NgSwitchCase  | 0.16
-[ ]  | core/testing/async  | 0.16
+[x]  | core/testing/async  | 0.16
 
 ## 翻译方式
 

packages/core/testing/src/async.ts

@@ -13,8 +13,13 @@ import {asyncFallback} from './async_fallback';
  * complete when all asynchronous calls within this zone are done. Can be used
  * to wrap an {@link inject} call.
  *
+ * 把一个测试函数包装进一个异步测试区域（Zone）。当该区域中的所有异步调用都已完成时，该测试将会自动完成。
+ * 可用于包装 {@link inject} 调用。
+ *
  * Example:
  *
+ * 例子：
+ *
  * ```
  * it('...', async(inject([AClass], (object) => {
  *   object.doSomething.then(() => {
@@ -42,4 +47,4 @@ export function async(fn: Function): (done: any) => any {
   // TODO @JiaLiPassion, remove this after all library updated to
   // newest version of zone.js(0.8.25)
   return asyncFallback(fn);
-}
+}