Remove Debug object from the user roots in heap profiler.

src/profile-generator.cc

Index: src/profile-generator.cc
diff --git a/src/profile-generator.cc b/src/profile-generator.cc
index ec08f8dca806b0f34985ca4dbd859b8e464ce9eb..9c50383e8ec3feb8282874cc742271a05c8d499f 100644
--- a/src/profile-generator.cc
+++ b/src/profile-generator.cc
@@ -34,6 +34,7 @@
 #include "scopeinfo.h"
 #include "unicode.h"
 #include "zone-inl.h"
+#include "debug.h"
 
 namespace v8 {
 namespace internal {
@@ -1986,7 +1987,15 @@ void V8HeapExplorer::ExtractReferences(HeapObject* obj) {
     // We use JSGlobalProxy because this is what embedder (e.g. browser)
     // uses for the global object.
     JSGlobalProxy* proxy = JSGlobalProxy::cast(obj);
-    SetWindowReference(proxy->map()->prototype());
+    Object* object = proxy->map()->prototype();
+    bool is_debug_object = false;
+#ifdef ENABLE_DEBUGGER_SUPPORT
+    is_debug_object = object->IsGlobalObject() &&
+        Isolate::Current()->debug()->IsDebugGlobal(GlobalObject::cast(object));
+#endif
+    if (!is_debug_object) {
+      SetUserGlobalReference(object);
+    }
   } else if (obj->IsJSObject()) {
     JSObject* js_obj = JSObject::cast(obj);
     ExtractClosureReferences(js_obj, entry);
@@ -2631,7 +2640,7 @@ void V8HeapExplorer::SetRootGcRootsReference() {
 }
 
 
-void V8HeapExplorer::SetWindowReference(Object* child_obj) {
+void V8HeapExplorer::SetUserGlobalReference(Object* child_obj) {
   HeapEntry* child_entry = GetEntry(child_obj);
   ASSERT(child_entry != NULL);
   filler_->SetNamedAutoIndexReference(