This implements support for the "throw" operation in the interpreter.
Note that support for catching/handling exceptions is still missing
from the interpreter in will be done separately.

This also introduces a {WasmExceptionPackage} class to the object model
that acts as an interface for allocating and accessing exceptions that
originate from WebAssembly. It does not represent a new instance type
however as exceptions are instances of {WebAssembly.RuntimeError} for
now.

R=clemensh@chromium.org
TEST=mjsunit/wasm/exceptions
BUG=v8:8091

Change-Id: I1f0cb548efb798e3c1488d42e4a31421c3c1aada
Reviewed-on: https://chromium-review.googlesource.com/c/1430099Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59033}