Provide private symbols through internal APIs

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index f7c89175da75c2fb7916015a34adf9954b565eef..85ae8fe54e87075ef8cf34b9b8749a8bde9caec9 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -1669,10 +1669,14 @@ void HeapObject::HeapObjectShortPrint(StringStream* accumulator) {
     }
     case SYMBOL_TYPE: {
       Symbol* symbol = Symbol::cast(this);
-      accumulator->Add("<Symbol: %d", symbol->Hash());
-      if (!symbol->name()->IsUndefined()) {
+      accumulator->Add("<");
+      accumulator->Add(symbol->IsPrivate() ? "Private" : "Symbol");
+      accumulator->Add(": %d", symbol->Hash());
+      Object* name =
+          symbol->IsPrivate() ? Private::cast(symbol)->name() : symbol->name();
+      if (!name->IsUndefined()) {
         accumulator->Add(" ");
-        String::cast(symbol->name())->StringShortPrint(accumulator);
+        String::cast(name)->StringShortPrint(accumulator);
       }
       accumulator->Add(">");
       break;