Reason for revert:
Breaks tree, i.e. https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20ASAN/builds/18928/steps/Check/logs/grow-memory
Original issue's description:
> [wasm] Initial signal handler
>
> This is basically the minimum viable signal handler for Wasm bounds checks.
> It includes the TLS check and the fine grained instructions checks. These
> two checks provide most of the safety for the signal handler. Future CLs will
> add code range and data range checks for more robustness.
>
> The trap handling code and data structures are all in src/trap-handler, with
> the code that actually runs in the signal handler confined to
> src/trap-handler/signal-handler.cc.
>
> This changes adds a new V8 API that the embedder should call from a signal
> handler that will give V8 the chance to handle the fault first. For hosts that
> do not want to implement their own signal handler, we include the option to
> install a simple one. This simple handler is also used for the tests.
>
> When a Wasm module is instantiated, information about each function is passed
> to the trap handler, which is used to classify faults. These are removed during
> the instance finalizer.
>
> Several future enhancements are planned before turning this on by default.
> Obviously, the additional checks will be added to MaybeHandleFault. We are
> also planning to add a two-level CodeObjectData table that is grouped by
> isolates to make cleanup easier and also reduce potential for contending on
> a single data structure.
>
> BUG= https://bugs.chromium.org/p/v8/issues/detail?id=5277
>
> Review-Url: https://codereview.chromium.org/2371833007
> Cr-Commit-Position: refs/heads/master@{#43523}
> Committed: a5af7fe9eeTBR=ahaas@chromium.org,bradnelson@google.com,hpayer@chromium.org,jochen@chromium.org,mark@chromium.org,mseaborn@chromium.org,titzer@chromium.org,eholk@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG= https://bugs.chromium.org/p/v8/issues/detail?id=5277
Review-Url: https://codereview.chromium.org/2723133003
Cr-Commit-Position: refs/heads/master@{#43525}
0b3e554e03