Upgrade Symbol implementation to match current ES6 behavior.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 713d4501ae5dfe521f6d28d743335366019db7a4..72d6ab2a5e6cabf863c33047938d11365e0d9f0e 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -629,7 +629,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_CreatePrivateSymbol) {
 }
 
 
-RUNTIME_FUNCTION(MaybeObject*, Runtime_SymbolName) {
+RUNTIME_FUNCTION(MaybeObject*, Runtime_SymbolDescription) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_CHECKED(Symbol, symbol, 0);
@@ -637,6 +637,30 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_SymbolName) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_SymbolSetSymbolData) {
+  HandleScope shs(isolate);
+  ASSERT(args.length() == 2);
+  CONVERT_ARG_CHECKED(JSObject, wrapper, 0);
+  CONVERT_ARG_CHECKED(Symbol, symbol, 1);
+  Handle<String> key(isolate->factory()->symbol_string());
+  Handle<JSObject> holder(wrapper, isolate);
+  Handle<Symbol> value(symbol, isolate);
+  JSObject::SetHiddenProperty(holder, key, value);
+  return isolate->heap()->undefined_value();
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_SymbolGetSymbolData) {
+  HandleScope shs(isolate);
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_CHECKED(JSObject, wrapper, 0);
+  Handle<String> key(isolate->factory()->symbol_string());
+  Handle<Object> result(wrapper->GetHiddenProperty(*key), isolate);
+  if (result->IsTheHole()) return isolate->heap()->undefined_value();
+  return *result;
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_SymbolIsPrivate) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 1);