This change does the following:

  a.) Remove unused fields from the Typer.
  b.) Move some interesting unions to types.h.
  c.) Reduce Typer constructor overhead.
  d.) Avoid heap allocation in the Typer.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1199903002

Cr-Commit-Position: refs/heads/master@{#29178}