Unfortunately, the problem here is that the combined worker will not be rebuilt if one of the modules it depends on changes.  For example, `createVerticesFromHeightmap` depends on `Core/Cartesian3`, which depends on `defaultValue`, etc., and so the combined file must be rebuilt when any of the files in the dependency graph changes.  One possibility might be to record this information somewhere based on the output of the r.js optimizer, and use that information to build a fileset to check for future updates.