Eliminate internal and hidden links to oddballs and other non-essential objects in heap snapshot.

src/profile-generator.h

Index: src/profile-generator.h
diff --git a/src/profile-generator.h b/src/profile-generator.h
index aee741f1d2e27690036d141ac2a67ca644bb7335..3b748e234f1823644325c6c2ef6ec069341ada66 100644
--- a/src/profile-generator.h
+++ b/src/profile-generator.h
@@ -980,6 +980,7 @@ class V8HeapExplorer : public HeapEntriesAllocator {
   void ExtractPropertyReferences(JSObject* js_obj, HeapEntry* entry);
   void ExtractElementReferences(JSObject* js_obj, HeapEntry* entry);
   void ExtractInternalReferences(JSObject* js_obj, HeapEntry* entry);
+  bool IsEssentialObject(Object* object);
   void SetClosureReference(HeapObject* parent_obj,
                            HeapEntry* parent,
                            String* reference_name,