The zone type cache would be handy inside the asm.js typer.
Pulling it out into a seperate inlinable header to allow sharing.

BUG=https://code.google.com/p/v8/issues/detail?id=4203
TEST=None
R=andreas@chromium.org,titzer@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1307093006

Cr-Commit-Position: refs/heads/master@{#30398}