Reland "[wasm] Publish new code from the background threads."

This is a reland of f991465b

Original change's description:
> [wasm] Publish new code from the background threads.
> 
> R=clemensh@chromium.org
> BUG=v8:7921
> 
> Change-Id: Ib86cb5f742907b6e54365827facfc765867ca22e
> Reviewed-on: https://chromium-review.googlesource.com/1156384
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#54985}

Bug: v8:7921
Change-Id: I08c5eb689fe4f8ef2f7b576f0145eb0ae617fd9d
Reviewed-on: https://chromium-review.googlesource.com/1170603Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55042}

src/compiler/wasm-compiler.cc

@@ -5172,6 +5172,7 @@ void TurbofanWasmCompilationUnit::ExecuteCompilation() {
     }
     if (ok_) wasm_code_ = info.wasm_code();
   }
+  if (ok_) wasm_unit_->native_module()->PublishCode(wasm_code_);
 }
 
 wasm::WasmCode* TurbofanWasmCompilationUnit::FinishCompilation(
@@ -5194,8 +5195,6 @@ wasm::WasmCode* TurbofanWasmCompilationUnit::FinishCompilation(
 
     return nullptr;
   }
-
-  wasm_unit_->native_module()->PublishCode(wasm_code_);
   return wasm_code_;
 }