ES6 symbols: implement name property

src/symbol.js

 // Copyright 2013 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 12 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 "use strict";
 
 var $Symbol = global.Symbol;
 
 function SymbolConstructor(x) {
-  var value = IS_SYMBOL(x) ? x : %CreateSymbol();
+  var value =
+    IS_SYMBOL(x) ? x : %CreateSymbol(IS_UNDEFINED(x) ? x : ToString(x));
   if (%_IsConstructCall()) {
     %_SetValueOf(this, value);
   } else {
     return value;
   }
 }
 
+function SymbolGetName() {
+  var symbol = IS_SYMBOL_WRAPPER(this) ? %_ValueOf(this) : this;
+  if (!IS_SYMBOL(symbol)) {
+    throw MakeTypeError(
+        'incompatible_method_receiver', ["Symbol.prototype.name", this]);
+
+  }
+  return %SymbolName(symbol);
+}
+
 function SymbolToString() {
   throw new $TypeError("Symbol.prototype.toString is not allowed");
 }
 
 function SymbolValueOf() {
   // NOTE: Both Symbol objects and values can enter here as
   // 'this'. This is not as dictated by ECMA-262.
   if (!IS_SYMBOL(this) && !IS_SYMBOL_WRAPPER(this)) {
     throw new $TypeError("Symbol.prototype.valueOf is not generic");
   }
   return %_ValueOf(this);
 }
 
 //-------------------------------------------------------------------
 
 function SetUpSymbol() {
   %CheckIsBootstrapping();
 
   %SetCode($Symbol, SymbolConstructor);
   %FunctionSetPrototype($Symbol, new $Symbol());
   %SetProperty($Symbol.prototype, "constructor", $Symbol, DONT_ENUM);
 
+  InstallGetter($Symbol.prototype, "name", SymbolGetName);
   InstallFunctions($Symbol.prototype, DONT_ENUM, $Array(
     "toString", SymbolToString,
     "valueOf", SymbolValueOf
   ));
 }
 
 SetUpSymbol();