Since I originally wrote, I've made a couple more changes:
I removed some unused data structures.
I disabled the 'large object' warnings, which in a modern browser (Chrome, Firefox, nightly builds of Safari) usually show up on top of the rendered object...making them kind of redundant.
In my analysis of https://github.com/tbuser/thingiview.js/issues#issue/4 I noted one bogus model that had "solid" in its first line, even though it was binary.
This fixes such models, by making the binary-vs.-ASCII decision slightly more complicated.