Fix Harmony sets and maps to allow undefined as keys.

src/collection.js

 // Copyright 2011 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 14 matching lines @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
 const $Set = global.Set;
 const $Map = global.Map;
 const $WeakMap = global.WeakMap;
 
 //-------------------------------------------------------------------
 
+// Global sentinel to be used instead of undefined keys, which are not
+// supported internally but required for Harmony sets and maps.
+var undefined_sentinel = {};
+
+
 function SetConstructor() {
   if (%_IsConstructCall()) {
     %SetInitialize(this);
   } else {
     return new $Set();
   }
 }
 
 
 function SetAdd(key) {
+  if (IS_UNDEFINED(key)) {
+    key = undefined_sentinel;
+  }
   return %SetAdd(this, key);
 }
 
 
 function SetHas(key) {
+  if (IS_UNDEFINED(key)) {
+    key = undefined_sentinel;
+  }
   return %SetHas(this, key);
 }
 
 
 function SetDelete(key) {
+  if (IS_UNDEFINED(key)) {
+    key = undefined_sentinel;
+  }
   return %SetDelete(this, key);
 }
 
 
 function MapConstructor() {
   if (%_IsConstructCall()) {
     %MapInitialize(this);
   } else {
     return new $Map();
   }
 }
 
 
 function MapGet(key) {
+  if (IS_UNDEFINED(key)) {
+    key = undefined_sentinel;
+  }
   return %MapGet(this, key);
 }
 
 
 function MapSet(key, value) {
+  if (IS_UNDEFINED(key)) {
+    key = undefined_sentinel;
+  }
   return %MapSet(this, key, value);
 }
 
 
 function MapHas(key) {
+  if (IS_UNDEFINED(key)) {
+    key = undefined_sentinel;
+  }
   return !IS_UNDEFINED(%MapGet(this, key));
 }
 
 
 function MapDelete(key) {
+  if (IS_UNDEFINED(key)) {
+    key = undefined_sentinel;
+  }
   if (!IS_UNDEFINED(%MapGet(this, key))) {
     %MapSet(this, key, void 0);
     return true;
   } else {
     return false;
   }
 }
 
 
 function WeakMapConstructor() {
@@ skipping 76 matching lines @@
   %SetProperty($WeakMap.prototype, "constructor", $WeakMap, DONT_ENUM);
 
   // Set up the non-enumerable functions on the WeakMap prototype object.
   InstallFunctionsOnHiddenPrototype($WeakMap.prototype, DONT_ENUM, $Array(
     "get", WeakMapGet,
     "set", WeakMapSet,
     "has", WeakMapHas,
     "delete", WeakMapDelete
   ));
 })();