Extends the current implementation of WASM exceptions to be able to
throw exceptions with values (not just tags).

An JS typed array (uint_16) is used to hold thrown values, so that the
thrown values can be inspected in JS.

Bug: v8:6577
Change-Id: I1007e79ceaffd64386b62562919cfbb920fc10c5
Reviewed-on: https://chromium-review.googlesource.com/633866
Commit-Queue: Karl Schimpf <kschimpf@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Eric Holk <eholk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48001}