Actually, if you are able to store and load dependency lists from r.js as I mentioned in another comment, that same behavior is what you want here too.  That is, the srcfiles fileset should be `Source/Cesium.js`, plus all dependencies detected the last time the file was combined.  

One thing I've been thinking about is limiting the set of modules that are attached directly to the global Cesium object.  For example, all the shader strings are attached to a `_shaders` subobject, but realistically, those strings are useless to external code, and shouldn't be part of the API.  So, the more robust approach is to trust the dependency list from r.js rather than filesets anyway.