Down-integrate changes from Kythe to the http_server code.

server/server.go

@@ -87,7 +87,7 @@ func main() {
 		}
 		defer db.Close()
 		tbl := &table.KVProto{db}
-		xs = &xsrv.Table{tbl}
+		xs = xsrv.NewCombinedTable(tbl)
 		ft = &ftsrv.Table{tbl}
 		esr = &esrchsrv.Table{&table.KVInverted{db}}