Combine TestLists (and maybe change format)?

Do people have thoughts on whether it would be ok to combine all the TestList files spread through the conformance suite into a single top-level file? It's a bit weird that the harness does all those fetches to build the master list.

Meanwhile, each of our browsers runs the tests offline in a more linear manner. It might be helpful to use a structured format like JSON for the test list, so that our platform testers could get the file and process it easier.