Support offset-TypedArray in futex API

src/futex-emulation.cc

 // Copyright 2015 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.
 
 #include "src/futex-emulation.h"
 
 #include <limits>
 
 #include "src/base/macros.h"
 #include "src/base/platform/time.h"
@@ skipping 244 matching lines @@
                                              Handle<JSArrayBuffer> array_buffer,
                                              size_t addr) {
   DCHECK(addr < NumberToSize(isolate, array_buffer->byte_length()));
   void* backing_store = array_buffer->backing_store();
 
   base::LockGuard<base::Mutex> lock_guard(mutex_.Pointer());
 
   int waiters = 0;
   FutexWaitListNode* node = wait_list_.Pointer()->head_;
   while (node) {
-    if (backing_store == node->backing_store_ && addr == node->wait_addr_) {
+    if (backing_store == node->backing_store_ && addr == node->wait_addr_ &&
+        node->waiting_) {
       waiters++;
     }
 
     node = node->next_;
   }
 
   return Smi::FromInt(waiters);
 }
 
 }  // namespace internal
 }  // namespace v8