Revert "[wasm][debug] Fix tier down during streaming compilation"

This reverts commit 3cc981cb.

Reason for revert: TSan failures: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN/31572

Original change's description:
> [wasm][debug] Fix tier down during streaming compilation
> 
> If the debugger is enabled while streaming compilation is happening, we
> won't correctly tier down to Liftoff. This is because during streaming
> compilation, we always compile for no debugging. Fixing that is a bit
> tricky, since when the debugger is enabled, functions can either already
> have finished compiling, or they are currently being compiled, or their
> wire bytes are not received yet.
> Instead of handling this correctly while streaming compilation is
> running, we just recompile the whole module with Liftoff after streaming
> compilation finished.
> 
> For testing this, we use the existing tests for async compilation, and
> enable --wasm-test-streaming, which compiles via the streaming decoder
> even in the async compilation case.
> 
> R=​thibaudm@chromium.org
> 
> Bug: v8:10531
> Change-Id: I0177248a9ad2e90f83faee965d6746de05423f1f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2207133
> Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#67882}

TBR=clemensb@chromium.org,thibaudm@chromium.org

Change-Id: I26e750c6c6d0783b5e4a0f19a5462a5fbe99a742
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10531
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2207186Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67885}

src/wasm/module-compiler.cc

@@ -802,9 +802,6 @@ class CompilationUnitBuilder {
     ExecutionTierPair tiers = GetRequestedExecutionTiers(
         native_module_->module(), compilation_state()->compile_mode(),
         native_module_->enabled_features(), func_index);
-    // Compile everything for non-debugging initially. If needed, we will tier
-    // down when the module is fully compiled. Synchronization would be pretty
-    // difficult otherwise.
     baseline_units_.emplace_back(func_index, tiers.baseline_tier, kNoDebugging);
     if (tiers.baseline_tier != tiers.top_tier) {
       tiering_units_.emplace_back(func_index, tiers.top_tier, kNoDebugging);
@@ -2409,13 +2406,6 @@ void AsyncStreamingProcessor::OnFinishedStream(OwnedVector<uint8_t> bytes) {
   }
   const bool needs_finish = job_->DecrementAndCheckFinisherCount();
   DCHECK_IMPLIES(!has_code_section, needs_finish);
-  // We might need to recompile the module for debugging, if the debugger was
-  // enabled while streaming compilation was running. Since handling this while
-  // compiling via streaming is tricky, we just tier down now, before publishing
-  // the module.
-  if (job_->native_module_->IsTieredDown()) {
-    job_->native_module_->TriggerRecompilation();
-  }
   if (needs_finish) {
     const bool failed = job_->native_module_->compilation_state()->failed();
     if (!cache_hit) {

test/debugger/debug/wasm/debug-enabled-tier-down-wasm-streaming.js

-// Copyright 2020 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Flags: --wasm-test-streaming
-
-load('test/debugger/debug/wasm/debug-enabled-tier-down-wasm.js');