vdl: Fix Javascript type generation bugs.

This fixes https://github.com/veyron/release-issues/issues/1202

A few of the issues resolved:
  1) Don't create type definitions for inner-types that aren't
     actually used at the top-level.
  2) Remove special-case for "error", which was causing a type
     definition to be generated for error unnecessarily.
  3) Remove wspr workaround.

Change-Id: I60e60db71605377f7e4f9bdd5c749fe442dac51c
MultiPart: 1/2
3 files changed