omit getInteropBlock

[emilos]

Hey,

thanks for the great tool. I'm trying to include rollup in a bigger app and I'd like to rewrite the files to es6 step by step. I'd like to start with views first, to transpile the files one by one, and later migrate more files to finally end up with a bundle. I was wondering if the following would make sense:

Here's a simplified case, given this input:

import View from 'core/view';
export default View.extend({});

I'd expect to have the following result:

define(['core/view'], function (View) {
      'use strict';

      return View.extend({});
});

however the result I'm getting right now is:

define(['core/view'], function (View) { 'use strict';
    View = 'default' in View ? View['default'] : View;
    var main = View.extend({});
    return main;
});

I'd like to omit the getInteropBlock step, to generate the code from the example 1 if possible for now. Would that make any sense or does that have some downsides? I'll happily create a PR if it makes sense.

[Rich-Harris]

I could get behind an interop: false option. A PR would be great, thank you!

There's a separate issue for the second part (avoiding the return main thing): #826