Support import() and import.meta

[eight]

import()

import("./foo.js").then(console.log);

to

myImport("./foo.js", document.currentScript.src).then(console.log);

import.meta

console.log(import.meta.url);

to

console.log(document.currentScript.src);

Throw other import.meta.*

---

Sometimes document.currentScript.src may not work e.g. in worker. We may need something like:

typeof document !== "undefined" && document.currentScript && document.currentScript.src || typeof location !== "undefined" && location.href || ""

We can use resolveImportMeta and renderDynamicImport.

[eight]

Dynamic import is deferred to #20.