This is a reland of b10a967f

Original change's description:
> [wasm] Add feature counter for threads and shared memory
> 
> This adds a feature counter for WASM shared memory (i.e. the presence
> of the "shared" bit in a WASM module's memory section) and the usage
> of WASM threads opcodes (i.e. wake/wait and atomics).
> 
> This CL also plumbs the WasmFeatures through the compilation pipeline
> to detect features as functions are being compiled.
> 
> R=ahaas@chromium.org, ulan@chromium.org
> BUG=chromium:868844
> 
> Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
> Change-Id: I854f932d3adb16e4fd87196fe2a193950295b856
> Reviewed-on: https://chromium-review.googlesource.com/1186329
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#55337}

Bug: chromium:868844
Change-Id: Iac3a38d80fa71aadd7147704669a8fd671ecfae8
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/1186343
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55363}