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

src/objects-debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 62 matching lines @@
 
 void HeapObject::HeapObjectVerify() {
   InstanceType instance_type = map()->instance_type();
 
   if (instance_type < FIRST_NONSTRING_TYPE) {
     String::cast(this)->StringVerify();
     return;
   }
 
   switch (instance_type) {
+    case SYMBOL_TYPE:
+      Symbol::cast(this)->SymbolVerify();
+      break;
     case MAP_TYPE:
       Map::cast(this)->MapVerify();
       break;
     case HEAP_NUMBER_TYPE:
       HeapNumber::cast(this)->HeapNumberVerify();
       break;
     case FIXED_ARRAY_TYPE:
       FixedArray::cast(this)->FixedArrayVerify();
       break;
     case FIXED_DOUBLE_ARRAY_TYPE:
@@ skipping 113 matching lines @@
   }
 }
 
 
 void HeapObject::VerifyHeapPointer(Object* p) {
   CHECK(p->IsHeapObject());
   CHECK(HEAP->Contains(HeapObject::cast(p)));
 }
 
 
+void Symbol::SymbolVerify() {
+  CHECK(IsSymbol());
+  CHECK(HasHashCode());
+  CHECK_GT(Hash(), 0);
+}
+
+
 void HeapNumber::HeapNumberVerify() {
   CHECK(IsHeapNumber());
 }
 
 
 void ByteArray::ByteArrayVerify() {
   CHECK(IsByteArray());
 }
 
 
@@ skipping 804 matching lines @@
   for (int i = 0; i < number_of_transitions(); ++i) {
     if (!CheckOneBackPointer(current_map, GetTarget(i))) return false;
   }
   return true;
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal