ES6 symbols: Introduce Symbol class, along with abstract Name class

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 45153ee0edbb759425442a5b4bb69a3c998f567e..7048af8f07ef500f0414eaac4ce747d6d8e98426 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -1318,6 +1318,9 @@ void HeapObject::HeapObjectShortPrint(StringStream* accumulator) {
         accumulator->Add("<Odd Oddball>");
       break;
     }
+    case SYMBOL_TYPE:
+      accumulator->Add("<Symbol: %d>", Symbol::cast(this)->Hash());
+      break;
     case HEAP_NUMBER_TYPE:
       accumulator->Add("<Number: ");
       HeapNumber::cast(this)->HeapNumberPrint(accumulator);
@@ -1426,6 +1429,7 @@ void HeapObject::IterateBody(InstanceType type, int object_size,
     case JS_GLOBAL_PROPERTY_CELL_TYPE:
       JSGlobalPropertyCell::BodyDescriptor::IterateBody(this, v);
       break;
+    case SYMBOL_TYPE:
     case HEAP_NUMBER_TYPE:
     case FILLER_TYPE:
     case BYTE_ARRAY_TYPE:
@@ -1480,6 +1484,12 @@ Object* HeapNumber::HeapNumberToBoolean() {
 }
 
 
+void Symbol::SymbolPrint(FILE* out) {
+  HeapObject::PrintHeader(out, "Symbol");
+  PrintF(out, " - hash: %d\n", Hash());
+}
+
+
 void HeapNumber::HeapNumberPrint(FILE* out) {
   PrintF(out, "%.16g", Number());
 }