Currently we expose sequence types via custom getters/setters in the JS bindings that map between the native WebCore collection types and JSArray (for examples, see SQLTransaction.idl and Clipboard.idl). It seems that the generated ObjC bindings for these files will not compile because the types exposed for these values in the IDL files (Array, ObjectArray) are unknown in ObjC-land. For now, we just aren't exposing bindings for those files (or, in the case of MessageEvent and the various instances of postMessage(), we are exposing a different set of non-array bindings for ObjC). When we add support for some kind of array type to the ObjC bindings generator, we should update MessageEvent and postMessage() to expose a uniform API for both sets of bindings.
Obj-C bindings are frozen.