ES6 symbols: Allow symbols as property names

src/v8globals.h

Index: src/v8globals.h
diff --git a/src/v8globals.h b/src/v8globals.h
index b86aa39952acd6e3f4327c7e1d1ec7b11d3e4381..8998e311fafd03fd4dc57d37b8158f1b6b704d0c 100644
--- a/src/v8globals.h
+++ b/src/v8globals.h
@@ -125,12 +125,13 @@ class FunctionTemplateInfo;
 class MemoryChunk;
 class SeededNumberDictionary;
 class UnseededNumberDictionary;
-class StringDictionary;
+class NameDictionary;
 template <typename T> class Handle;
 class Heap;
 class HeapObject;
 class IC;
 class InterceptorInfo;
+class JSReceiver;
 class JSArray;
 class JSFunction;
 class JSObject;
@@ -152,6 +153,7 @@ class Smi;
 template <typename Config, class Allocator = FreeStoreAllocationPolicy>
     class SplayTree;
 class String;
+class Name;
 class Struct;
 class Variable;
 class RelocInfo;