Nick Fitzgerald dff9b9b1e3 Don't put anything before ES module imports
Because of some incorrect use of `js.push_str(..)`, we could sometimes emit code
before the ES modules imports, which is syntactically invalid:

    const __exports = {};
    import { Thing } from '...'; // Syntax error!

This has been fixed by making sure that the correct `imports` or `imports_post`
string is built up. We now also assert that the `js` string is empty at the
location where we add imports if we're using ES modules.
2019-04-04 15:53:43 -07:00
..