revert this.async (avoid may breaking change)
revert this.async (avoid may breaking change)

halfzebra/webpack,halfzebra/webpack,ts-webpack/webpack,NekR/webpack,pugnascotia/webpack,ts-webpack/webpack,webpack/webpack,EliteScientist/webpack,webpack/webpack,g0ddish/webpack,webpack/webpack,pugnascotia/webpack,webpack/webpack,ts-webpack/webpack,rlugojr/webpack,g0ddish/webpack,jescalan/webpack,nkzawa/webpack,g0ddish/webpack,SimenB/webpack,cesarandreu/webpack,cesarandreu/webpack,pugnascotia/webpack,SimenB/webpack,jescalan/webpack,nkzawa/webpack,cesarandreu/webpack,nkzawa/webpack,SimenB/webpack,ts-webpack/webpack,jescalan/webpack,NekR/webpack,SimenB/webpack,halfzebra/webpack,EliteScientist/webpack,rlugojr/webpack,rlugojr/webpack