Fix for issue #28606. Removed loop which iterated over all threads in the thread registry to check …

runtime/vm/thread_registry.cc

Index: runtime/vm/thread_registry.cc
diff --git a/runtime/vm/thread_registry.cc b/runtime/vm/thread_registry.cc
index 32d48a4c0b553f2103e710b0d55925d8fddc6094..50856427bb1e023ec6dbe79670f5918d37924d56 100644
--- a/runtime/vm/thread_registry.cc
+++ b/runtime/vm/thread_registry.cc
@@ -105,19 +105,6 @@ void ThreadRegistry::PrintJSON(JSONStream* stream) const {
 #endif
 
 
-bool ThreadRegistry::IsValidHandle(Dart_Handle handle) const {
-  MonitorLocker ml(threads_lock());
-  Thread* current = active_list_;
-  while (current != NULL) {
-    if (current->IsValidHandle(handle)) {
-      return true;
-    }
-    current = current->next_;
-  }
-  return false;
-}
-
-
 intptr_t ThreadRegistry::CountZoneHandles() const {
   MonitorLocker ml(threads_lock());
   intptr_t count = 0;