I thought about that while I was writing it (I started before your challenge came out). Here's the results for ArcLite:

  > wc [^j]*.js
   66   147  1359 buffer.js
  369  1114 10672 eval.js
  149   488  4522 primitives.js
  188   509  4989 reader.js
  356  1145 11869 types.js
  136   370  3260 utils.js
 1264  3773 36671 total

 > wc [^d]*.scm
 1093  4404 36047 ac.scm
   16    30   242 as.scm
   48   152  1252 brackets.scm
 1157  4586 37541 total

So ArcLite is about 100 lines of code more. OTOH, if you take out the reader (which is supplied by Scheme but I had to write myself for ArcLite) it's -254 lines for ArcLite and -48 lines for Arc0. Which means the JavaScript version is actually smaller, at least in line count. (There's also the matter of the missing I/O primitives, but most of them just delegate to Scheme in Arc0 as well.)

I have no idea how it compares in code-tree count. Probably larger, as my JavaScript coding style is fairly dense. One could argue that that's the point of syntax though; it makes common operations take up very little space on the page.