Incremental builds

[OliverJAsh]

It is now possible to do incremental builds, i.e. https://github.com/jackfranklin/jspm-dev-builder:

const builder = new jspm.Builder();

function build(changedModuleId) {
    builder.invalidate(changedModuleId);
    return builder.build('main', 'out');
}

build();

// and again, but this time we only need to rebuild the file that changed
build('foo');

Do you think it's possible to incorporate this somehow, for use when paired with a watch task?