Spec adjustments for well-known symbols

src/symbol.js

Index: src/symbol.js
diff --git a/src/symbol.js b/src/symbol.js
index 49f909694c19f3ee44c60a39def7fbbd0f39c6a5..7bf10d1288967c222108c451f987735e2420b2b4 100644
--- a/src/symbol.js
+++ b/src/symbol.js
@@ -65,7 +65,7 @@ function SymbolValueOf() {
 
 function GetSymbolRegistry() {
   var registry = %SymbolRegistry();
-  if (!('internal' in registry)) {
+  if (IS_UNDEFINED(registry.internal)) {
     registry.internal = {__proto__: null};
     registry.for = {__proto__: null};
     registry.keyFor = {__proto__: null};
@@ -76,7 +76,7 @@ function GetSymbolRegistry() {
 
 function InternalSymbol(key) {
   var registry = GetSymbolRegistry();
-  if (!(key in registry.internal)) {
+  if (IS_UNDEFINED(registry.internal[key])) {
     registry.internal[key] = %CreateSymbol(key);
   }
   return registry.internal[key];
@@ -86,7 +86,7 @@ function InternalSymbol(key) {
 function SymbolFor(key) {
   key = TO_STRING_INLINE(key);
   var registry = GetSymbolRegistry();
-  if (!(key in registry.for)) {
+  if (IS_UNDEFINED(registry.for[key])) {
     var symbol = %CreateSymbol(key);
     registry.for[key] = symbol;
     registry.keyFor[symbol] = key;
@@ -118,13 +118,13 @@ function ObjectGetOwnPropertySymbols(obj) {
 
 //-------------------------------------------------------------------
 
-var symbolCreate = InternalSymbol("@@create");
-var symbolHasInstance = InternalSymbol("@@hasInstance");
-var symbolIsConcatSpreadable = InternalSymbol("@@isConcatSpreadable");
-var symbolIsRegExp = InternalSymbol("@@isRegExp");
-var symbolIterator = InternalSymbol("@@iterator");
-var symbolToStringTag = InternalSymbol("@@toStringTag");
-var symbolUnscopables = InternalSymbol("@@unscopables");
+var symbolCreate = InternalSymbol("Symbol.create");
+var symbolHasInstance = InternalSymbol("Symbol.hasInstance");
+var symbolIsConcatSpreadable = InternalSymbol("Symbol.isConcatSpreadable");
+var symbolIsRegExp = InternalSymbol("Symbol.isRegExp");
+var symbolIterator = InternalSymbol("Symbol.iterator");
+var symbolToStringTag = InternalSymbol("Symbol.toStringTag");
+var symbolUnscopables = InternalSymbol("Symbol.unscopables");
 
 
 //-------------------------------------------------------------------
@@ -135,14 +135,15 @@ function SetUpSymbol() {
   %SetCode($Symbol, SymbolConstructor);
   %FunctionSetPrototype($Symbol, new $Object());
 
-  %SetProperty($Symbol, "create", symbolCreate, DONT_ENUM);
-  %SetProperty($Symbol, "hasInstance", symbolHasInstance, DONT_ENUM);
-  %SetProperty($Symbol, "isConcatSpreadable",
-      symbolIsConcatSpreadable, DONT_ENUM);
-  %SetProperty($Symbol, "isRegExp", symbolIsRegExp, DONT_ENUM);
-  %SetProperty($Symbol, "iterator", symbolIterator, DONT_ENUM);
-  %SetProperty($Symbol, "toStringTag", symbolToStringTag, DONT_ENUM);
-  %SetProperty($Symbol, "unscopables", symbolUnscopables, DONT_ENUM);
+  InstallConstants($Symbol, $Array(
+    "create", symbolCreate,
+    "hasInstance", symbolHasInstance,
+    "isConcatSpreadable", symbolIsConcatSpreadable,
+    "isRegExp", symbolIsRegExp,
+    "iterator", symbolIterator,
+    "toStringTag", symbolToStringTag,
+    "unscopables", symbolUnscopables
+  ));
   InstallFunctions($Symbol, DONT_ENUM, $Array(
     "for", SymbolFor,
     "keyFor", SymbolKeyFor