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 3e8d57d039900ac11fc0311b9a45ba35045f9f43..7aa28da6b916a36be666c6bedd1f860cca47d329 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -633,7 +633,14 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_CreatePrivateSymbol) {
 }
 
 
-RUNTIME_FUNCTION(MaybeObject*, Runtime_SymbolName) {
+RUNTIME_FUNCTION(MaybeObject*, Runtime_NewSymbolWrapper) {
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_CHECKED(Symbol, symbol, 0);
+  return symbol->ToObject(isolate);
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_SymbolDescription) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_CHECKED(Symbol, symbol, 0);
@@ -11264,15 +11271,18 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetFrameDetails) {
   // THIS MUST BE DONE LAST SINCE WE MIGHT ADVANCE
   // THE FRAME ITERATOR TO WRAP THE RECEIVER.
   Handle<Object> receiver(it.frame()->receiver(), isolate);
-  if (!receiver->IsJSObject() &&
-      shared->is_classic_mode() &&
-      !function->IsBuiltin()) {
+  if (receiver->IsSymbol() ||
+      (!receiver->IsJSObject() &&
+       shared->is_classic_mode() &&
+       !function->IsBuiltin())) {
     // If the receiver is not a JSObject and the function is not a
     // builtin or strict-mode we have hit an optimization where a
     // value object is not converted into a wrapped JS objects. To
     // hide this optimization from the debugger, we wrap the receiver
     // by creating correct wrapper object based on the calling frame's
     // native context.
+    // Symbol receivers are always exempted as their (strict) builtins
+    // only work over the wrapped form.
     it.Advance();
     if (receiver->IsUndefined()) {
       Context* context = function->context();