This shares {NativeModule} and associated {WasmCode} objects across
multiple WebAssembly instances in the same Isolate. It also removes
support for cloning the aforementioned objects.

R=clemensh@chromium.org
BUG=v8:7424

Change-Id: I35334bd68f87e5871c244ee33dfcecb9da326b9f
Reviewed-on: https://chromium-review.googlesource.com/1032780
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52877}