Bug 972606, part 1 - Convert nsJAR::mManifestData to nsClassHashtable. r=aklotz
Bug 972606, part 2 - Take advantage of infallible new in nsJAR. r=aklotz

Plus a few minor fixups in the header.
Bug 972591, part 3 - Convert nsXBLDocumentInfo::mBindingTable to nsClassHashtable. r=froydnj,bz