Do not apply top-level transforms to builtins

Currently, transforms are being attempted on builtins.  However, resolution of that transform usually fails, because it can't be resolved from the builtin path.

For example, the builtin path is:
/Projects/node/browser-builtins/builtin/querystring.js

But the transform is located in:
/Projects/js/foo/node_modules/deamdify/index.js

I'm not sure I like the approach of hardcoding `browser-builtins` as a path.  All the other methods I tried quickly became overcomplicated.

Good enough?  Other suggestions?