This CL adds a basic tiering strategy for the js-to-wasm wrappers.
When applicable, calls to exported WebAssembly functions are initially
handled through the generic js-to-wasm wrapper. If these calls
through the generic wrapper reach a constant threshold, the specific
(per-signature) wrapper is compiled synchronously for the function
and the generic wrapper is replaced.

Bug: v8:10982
Change-Id: I65e706daffb5cb6e723ce2f7b785f7ecb7b2fa7b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2461243
Commit-Queue: Vicky Kontoura <vkont@google.com>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70503}