Associate a type with foreign functions at their callsite.
Associate a type with foreign variables.
More pervasively forbid computation in the module body.
Confirm foreign call arguments are exports.

BUG= https://code.google.com/p/v8/issues/detail?id=4203
TEST=test-asm-validator
R=aseemgarg@chromium.org,titzer@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1642993002

Cr-Commit-Position: refs/heads/master@{#33596}