Added code to trace zone and handles creation/deletion under flags

vm/handles.cc

 // Copyright (c) 2012, 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/handles.h"
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/flags.h"
 #include "vm/isolate.h"
 #include "vm/os.h"
 #include "vm/raw_object.h"
 #include "vm/visitor.h"
 #include "vm/zone.h"
 
 #include "vm/handles_impl.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, verify_handles, false, "Verify handles.");
-DEFINE_DEBUG_FLAG(bool, trace_handles_count,
-                  false, "Trace count of handles allocated.");
+DEFINE_DEBUG_FLAG(bool, trace_handles,
+                  false, "Traces allocation of handles.");
 
 
 VMHandles::~VMHandles() {
+#ifdef DEBUG
+    if (FLAG_trace_handles) {
+      OS::PrintErr("***   Handle Counts for 0x(%"Px"):Zone = %d,Scoped = %d\n",
+                   reinterpret_cast<intptr_t>(this),
+                   CountZoneHandles(), CountScopedHandles());
+      OS::PrintErr("*** Deleting VM handle block 0x%"Px"\n",
+                   reinterpret_cast<intptr_t>(this));
+    }
+#endif
 }
 
 
 void VMHandles::VisitObjectPointers(ObjectPointerVisitor* visitor) {
   return Handles<kVMHandleSizeInWords,
                  kVMHandlesPerChunk,
                  kOffsetOfRawPtr>::VisitObjectPointers(visitor);
 }
 
 
@@ skipping 72 matching lines @@
   isolate()->IncrementNoHandleScopeDepth();
 }
 
 
 NoHandleScope::~NoHandleScope() {
   isolate()->DecrementNoHandleScopeDepth();
 }
 #endif  // defined(DEBUG)
 
 }  // namespace dart