The addition of assert functions to Userland/js was done before we had load(..) implemented. Now that it exists, it seems like the right move the test helper functions to pure javascript instead of poluting js with random global functions.
Switch the LibJS test suite to use the native assert implementation surfaced inside the js repl when it's launched in test mode.
"feature-basic" is a bit more logical than having a ton of "basic-feature" (when it comes to the visual overview of it all.)
