deps: V8: use ATOMIC_VAR_INIT instead of std::atomic_init

`std::atomic_init<size_t>` is not implemented on all platforms.

Backport-PR-URL: #30109
PR-URL: #27375
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

common.gypi

@@ -38,7 +38,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.5',
+    'v8_embedder_string': '-node.6',
 
     ##### V8 defaults for Node.js #####
 

deps/v8/src/wasm/module-compiler.cc

@@ -152,9 +152,6 @@ class CompilationUnitQueues {
     for (int task_id = 0; task_id < max_tasks; ++task_id) {
       queues_[task_id].next_steal_task_id = next_task_id(task_id);
     }
-    for (auto& atomic_counter : num_units_) {
-      std::atomic_init(&atomic_counter, size_t{0});
-    }
   }
 
   base::Optional<WasmCompilationUnit> GetNextUnit(
@@ -257,14 +254,15 @@ class CompilationUnitQueues {
   };
 
   struct BigUnitsQueue {
-    BigUnitsQueue() {
-      for (auto& atomic : has_units) std::atomic_init(&atomic, false);
-    }
+    BigUnitsQueue() = default;
 
     base::Mutex mutex;
 
     // Can be read concurrently to check whether any elements are in the queue.
-    std::atomic<bool> has_units[kNumTiers];
+    std::atomic_bool has_units[kNumTiers] = {
+      ATOMIC_VAR_INIT(false),
+      ATOMIC_VAR_INIT(false)
+    };
 
     // Protected by {mutex}:
     std::priority_queue<BigUnit> units[kNumTiers];
@@ -273,8 +271,11 @@ class CompilationUnitQueues {
   std::vector<Queue> queues_;
   BigUnitsQueue big_units_queue_;
 
-  std::atomic<size_t> num_units_[kNumTiers];
-  std::atomic<int> next_queue_to_add{0};
+  std::atomic_size_t num_units_[kNumTiers] = {
+    ATOMIC_VAR_INIT(0),
+    ATOMIC_VAR_INIT(0)
+  };
+  std::atomic_int next_queue_to_add{0};
 
   int next_task_id(int task_id) const {
     int next = task_id + 1;
@@ -481,7 +482,7 @@ class CompilationStateImpl {
 
   // Compilation error, atomically updated. This flag can be updated and read
   // using relaxed semantics.
-  std::atomic<bool> compile_failed_{false};
+  std::atomic_bool compile_failed_{false};
 
   const int max_background_tasks_ = 0;