ES6 symbols: implement name property

src/objects-printer.cc

Index: src/objects-printer.cc
diff --git a/src/objects-printer.cc b/src/objects-printer.cc
index 4522ee43e513f4dee1d2288c25d4d95a5aa05cdb..86382e1d54188ed119925369f5d224323f6eae0b 100644
--- a/src/objects-printer.cc
+++ b/src/objects-printer.cc
@@ -552,6 +552,9 @@ static const char* TypeToString(InstanceType type) {
 void Symbol::SymbolPrint(FILE* out) {
   HeapObject::PrintHeader(out, "Symbol");
   PrintF(out, " - hash: %d\n", Hash());
+  PrintF(out, " - name: ");
+  name()->ShortPrint();
+  PrintF(out, "\n");
 }