prerocess export import declarations correctly

[mhegazy]

fixes #4727

[DanielRosenwasser]

It would be great if you had a helper function like

function scanYieldsSequence(scanner: Scanner, seq: (SyntaxKind | ((kind: SyntaxKind) => boolean))[]) {
    for (let item of seq) {
        let passes = item instanceof Function ?
            item(scanner.scan()) :
            item === scanner.scan()
        if (!passes) {
            return false;
        }
    }

    return true;
}

but it might be overkill

[mhegazy]

yes, and yes :)

[DanielRosenwasser]

👍