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

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index bafd5888fe2f840319add622aedfa1672564417d..34b2c71469c39fecf3495bb4b0262c254c0f5e18 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -4191,7 +4191,7 @@ class Internals {
   static const int kNullValueRootIndex = 7;
   static const int kTrueValueRootIndex = 8;
   static const int kFalseValueRootIndex = 9;
-  static const int kEmptyStringRootIndex = 118;
+  static const int kEmptyStringRootIndex = 119;
 
   static const int kNodeClassIdOffset = 1 * kApiPointerSize;
   static const int kNodeFlagsOffset = 1 * kApiPointerSize + 3;
@@ -4201,10 +4201,10 @@ class Internals {
   static const int kNodeIsIndependentShift = 4;
   static const int kNodeIsPartiallyDependentShift = 5;
 
-  static const int kJSObjectType = 0xab;
+  static const int kJSObjectType = 0xac;
   static const int kFirstNonstringType = 0x80;
-  static const int kOddballType = 0x82;
-  static const int kForeignType = 0x85;
+  static const int kOddballType = 0x83;
+  static const int kForeignType = 0x86;
 
   static const int kUndefinedOddballKind = 5;
   static const int kNullOddballKind = 3;