Optimize Map/Set.prototype.forEach

src/collection.js

Index: src/collection.js
diff --git a/src/collection.js b/src/collection.js
index 0d8dd77f7bd3be944ffcd25b51544d8ebe740c00..ca31152d89d5a5410f2f24203872269d9b9441c1 100644
--- a/src/collection.js
+++ b/src/collection.js
@@ -80,11 +80,13 @@ function SetForEach(f, receiver) {
   }
 
   var iterator = new SetIterator(this, ITERATOR_KIND_VALUES);
-  var entry;
+  var key;
   var stepping = %_DebugCallbackSupportsStepping(f);
-  while (!(entry = %SetIteratorNext(iterator)).done) {
+  while (%SetIteratorHasMore(iterator)) {
+    key = %SetIteratorCurrentKey(iterator);
+    %SetIteratorMoveNext(iterator);
     if (stepping) %DebugPrepareStepInIfStepping(f);
-    %_CallFunction(receiver, entry.value, entry.value, this, f);
+    %_CallFunction(receiver, key, key, this, f);
   }
 }
 
@@ -191,17 +193,21 @@ function MapForEach(f, receiver) {
   }
 
   var iterator = new MapIterator(this, ITERATOR_KIND_ENTRIES);
-  var entry;
+  var key, value;
   var stepping = %_DebugCallbackSupportsStepping(f);
-  while (!(entry = %MapIteratorNext(iterator)).done) {
+  while (%MapIteratorHasMore(iterator)) {
+    key = %MapIteratorCurrentKey(iterator);
+    value = %MapIteratorCurrentValue(iterator);
+    %MapIteratorMoveNext(iterator);
     if (stepping) %DebugPrepareStepInIfStepping(f);
-    %_CallFunction(receiver, entry.value[1], entry.value[0], this, f);
+    %_CallFunction(receiver, value, key, this, f);
   }
 }
 
 
 // -------------------------------------------------------------------
 
+
 function SetUpMap() {
   %CheckIsBootstrapping();