[wasm] Reenable tier-up

The AsyncCompileJob should not cancel compilation if baseline
compilation already finished. At that point, we might still be tiering
up, and the module might even already be shared across isolates.

R=titzer@chromium.org
CC=ahaas@chromium.org

Bug: v8:8677, v8:8689
Change-Id: Ia2192a1985bf4a3b7125ce5a713c83bbcc1bf6b7
Reviewed-on: https://chromium-review.googlesource.com/c/1417931
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58916}

src/wasm/module-compiler.cc

@@ -924,7 +924,11 @@ std::shared_ptr<StreamingDecoder> AsyncCompileJob::CreateStreamingDecoder() {
 
 AsyncCompileJob::~AsyncCompileJob() {
   background_task_manager_.CancelAndWait();
-  if (native_module_) Impl(native_module_->compilation_state())->Abort();
+  // If the runtime objects were not created yet, then initial compilation did
+  // not finish yet. In this case we can abort compilation.
+  if (native_module_ && module_object_.is_null()) {
+    Impl(native_module_->compilation_state())->Abort();
+  }
   // Tell the streaming decoder that the AsyncCompileJob is not available
   // anymore.
   // TODO(ahaas): Is this notification really necessary? Check
@@ -1042,12 +1046,8 @@ class AsyncCompileJob::CompilationStateCallback {
         break;
       case CompilationEvent::kFinishedTopTierCompilation:
         DCHECK_EQ(CompilationEvent::kFinishedBaselineCompilation, last_event_);
-        // If a foreground task or a finisher is pending, we rely on
-        // FinishModule to remove the job.
-        if (!job_->pending_foreground_task_ &&
-            job_->outstanding_finishers_.load() == 0) {
-          job_->isolate_->wasm_engine()->RemoveCompileJob(job_);
-        }
+        // This callback should not react to top tier finished callbacks, since
+        // the job might already be gone then.
         break;
       case CompilationEvent::kFailedCompilation:
         DCHECK(!last_event_.has_value());