Recompiles are not triggered when dependencies change if no entryPoint

[elldritch]

If I don't manually specify my bundles using the { bundles: { 'output.js': {entryPoints: ['entry-point.js']}}} options syntax and instead opt for the {bundleExtension: '.bundle', outputExtension: '.es5'} options syntax, then recompiles will not be triggered when my dependencies change. A simple example:

With a.js and b.js where:

// a.js
console.log(require('./b'));

// b.js
module.exports = 'foo';

If I change b.js to module.exports = 'bar'; then a.js will not recompile to reflect this change.