function parseBundleDependencies (pkgJson) {
	const bundleDependencies = []
		.concat(pkgJson.bundleDependencies || [])
		.concat(pkgJson.bundledDependencies || [])
	return bundleDependencies
}
extract an array of bundled dependency names from the passed in
`package.json`. uses the `bundleDependencies` and `bundledDependencies`
properties.
@param  {Object} pkgJson - plain JavaScript object representing a
`package.json` file.
@return {Array.<String>} - array of bundled dependency names.