Instead of using injectAsync and returning a promise, use the `async` function
to wrap tests. This will run the test inside a zone which does not complete
the test until all asynchronous tasks have been completed.
`async` may be used with the `inject` function, or separately.
BREAKING CHANGE:
`injectAsync` is now deprecated. Instead, use the `async` function
to wrap any asynchronous tests.
Before:
```
it('should wait for returned promises', injectAsync([FancyService], (service) => {
return service.getAsyncValue().then((value) => { expect(value).toEqual('async value'); });
}));
it('should wait for returned promises', injectAsync([], () => {
return somePromise.then(() => { expect(true).toEqual(true); });
}));
```
After:
```
it('should wait for returned promises', async(inject([FancyService], (service) => {
service.getAsyncValue().then((value) => { expect(value).toEqual('async value'); });
})));
// Note that if there is no injection, we no longer need `inject` OR `injectAsync`.
it('should wait for returned promises', async(() => {
somePromise.then() => { expect(true).toEqual(true); });
}));
```
Closes#7735