be interactive

would be nice if this could execute the js as you stream it to it instead of buffering the entire source.
it could probably be executed like this

``` js
try {
eval(sourceBuffer)
} catch (e) {
if (e.name === 'SyntaxError') {
// bufferMore
return
} else {
throw err
}
}
sourceBuffer = ''
```

The issue names no files or tests. Start by locating the streaming wrapper and the path that buffers incoming JavaScript, then verify how incomplete SyntaxError input is distinguished from runtime errors. Done means JavaScript executes incrementally while streaming, without buffering the entire source, with behavior covered by the repository's test suite.

Written by the indexing model from the issue text.