WIP(async): support native async/await

[JiaLiPassion]

fix #740, #795.

I think I may find a way to resolve native async/await issue.
The test code below works well.

  async function test() {
            console.log('test');
            return 1;
        }

        async function test1() {
            console.log('before await test', Zone.current.name);
            const result = await test();
            // should keep zone context test
            console.log('after await test', result, Zone.current.name);
        }

        async function test2() {
            console.log('before await test1', Zone.current.name);
            const result = await test1();
            // should keep zone context test
            console.log('after await test1', result, Zone.current.name);
        }
        console.log('begin test');
        Zone.current.fork({name: 'test'}).run(test1);
        // here should be <root> zone.
        console.log('outside test', Zone.current.name);
        Zone.current.fork({name: 'test1'}).run(() => {
            // should be test1 zone.
            console.log('another test', Zone.current.name);
        });

@mhevery, I will continue to add test cases, hope it can work.

[KrzysztofKarol]

Hi @JiaLiPassion, do you have any update on this?

[jguyenot]

Hi @JiaLiPassion have you time to correct integrations fails?

[JiaLiPassion]

@KrzysztofKarol , @jguyenot , there are some cases this solution will not work, I will continue to find another solution, thanks!

[jguyenot]

Thanks for your time. It's actually impossible to implement lazy loading module with angular 8 and zone.js so it's very important.
Good luck.