This CL updates the hook for the WebAssembly spec repository, and it
updates the WebAssembly spec tests. The WebAssembly spec tests have to
be updated manually with the tools/wasm/update-wasm-spec-tests.sh
script. Mircea, I saw that you updated the WebAssembly spec repository
last time. Can you please take a look?

UPDATE: I improved the update script slightly, and there is one
additional JS API test we fail now and have to fix eventually.

R=mtrofin@chromium.org

Change-Id: I3c0df9cee64d444147db47daa0c1936edf116173
Reviewed-on: https://chromium-review.googlesource.com/509257Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45692}