This is primarily to aid in testing the Wasm out of bounds trap handler.  We
keep track of how many faults have been recovered by the Wasm trap handler. This
count is exposed to JavaScript through a testing-only runtime function. This
allows tests to verify whether the trap handler is actually running.

Bug: v8:5277
Change-Id: Ie8037a36d84eb08166c6e40c7225d912683d5786
Reviewed-on: https://chromium-review.googlesource.com/665968
Commit-Queue: Eric Holk <eholk@chromium.org>
Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48076}