Add a mid-sized integration test for the Dart Embedding Api which

runtime/vm/port.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/port.h"
 
 #include "vm/isolate.h"
 #include "vm/thread.h"
 #include "vm/utils.h"
 
@@ skipping 72 matching lines @@
   } else if (empty < deleted_) {
     // Rehash without growing the table to flush the deleted slots out of the
     // map.
     Rehash(capacity_);
   }
 }
 
 
 Dart_Port PortMap::CreatePort() {
   Isolate* isolate = Isolate::Current();
-
   MutexLocker ml(mutex_);
 
   Entry entry;
   entry.port = AllocatePort();
   entry.isolate = isolate;
 
   // Search for the first unused slot. Make use of the knowledge that here is
   // currently no port with this id in the port map.
   ASSERT(FindPort(entry.port) < 0);
   intptr_t index = entry.port % capacity_;
@@ skipping 51 matching lines @@
   // Notify the embedder that this port is closed.
   Dart_ClosePortCallback callback = isolate->close_port_callback();
   ASSERT(callback);
   ASSERT(port != kCloseAllPorts);
   (*callback)(isolate, port);
 }
 
 
 void PortMap::ClosePorts() {
   Isolate* isolate = Isolate::Current();
+  if (isolate->active_ports() == 0) {
+    return;
+  }
   {
     MutexLocker ml(mutex_);
     for (intptr_t i = 0; i < capacity_; i++) {
       if (map_[i].isolate == isolate) {
         // Mark the slot as deleted.
         map_[i].port = 0;
         map_[i].isolate = deleted_entry_;
         isolate->decrement_active_ports();
 
         used_--;
@@ skipping 50 matching lines @@
   ASSERT(Utils::IsPowerOfTwo(kInitialCapacity));
   map_ = new Entry[kInitialCapacity];
   memset(map_, 0, kInitialCapacity * sizeof(Entry));
   capacity_ = kInitialCapacity;
   used_ = 0;
   deleted_ = 0;
 }
 
 
 }  // namespace dart