特性请求: <await> 中的 Stale-while-revalidate

Description

This weekend I toyed with a simple auto complete demo. Now that we live in a utopian world with client-side <await>, I wanted to make the implementation as declarative as possible. [Example](https://markojs.com/playground#djIfiwgAAAAAAAATXZAxT8MwEIX_ysliSKWqZmBAJQkMLGyA2BoG17m2Fq4d7DNQtf3vXJxQtWzn8733vbvFXnSKNmIujGvxZ7ZV4cOLqdDeETrifmmR5GfCsKsa0Yi6caVxXaLGAdCuQ-5GVEFv-JdbX8omnFdZALLuW42LpMhoYCcgs0Wf6OkRKnDJ2jv26wktLn1yGtuXC1TUwXSUbc6VEelteBbFBKoa9nBpwDM5wnEKN9fXk15_Fc3aKTvzTi19IJ4YpNpy_D-3E4QlpTzRTyuouHMaVgwi4x2skV4xJkuxyLgJ7HuU-laGwOE3PAe_NRGLImD09gsz8Sz92J7CLafMMQNSCg4WjVhyrkZMgau0HgtEstiI934SYLYyljAU-ei9cy5mxmmbWvzLxLZH3obCLt-xzOkOYch9qM52uLzhpB4o5cqHcfwAflWNyvGX_62pr_ZD91hKfo06ycIBKTNzqB86qzRuvG0xjJNSglWR-sPwei2MBLi_H9T_JKXsdxHH91-K0YSJvgIAAA