jscript: Get rid of no longer needed compile_interp_fallback since we can handle all execution by bytecode.

We use compiler on whole functions body now. There is still some work
done to move it one level up (to whole source string) to do some work
that's currently done (sometimes in a hacky way) by parser, but the most
critical part is done.

Use sentence capitalization for group box labels.
Don't assign access keys to group box labels.
Don't pad group box labels with spaces.