extensions/emmet/src/locateFile.ts/locateFile
export function locateFile(base: string, filePath: string): Promise<string> {
	if (/^\w+:/.test(filePath)) {
		// path with protocol, already absolute
		return Promise.resolve(filePath);
	}

	filePath = path.normalize(filePath);

	return reAbsolute.test(filePath)
		? resolveAbsolute(base, filePath)
		: resolveRelative(base, filePath);
}