Merge m-c to Ionmonkey.

js/src/jsiter.cpp

@@ -804,11 +804,21 @@ iterator_iterator(JSContext *cx, HandleObject obj, JSBool keysonly)
 static JSBool
 Iterator(JSContext *cx, unsigned argc, Value *vp)
 {
-    Value *argv = JS_ARGV(cx, vp);
-    bool keyonly = argc >= 2 ? js_ValueToBoolean(argv[1]) : false;
+    CallArgs args = CallArgsFromVp(argc, vp);
+    if (args.length() == 0) {
+        js_ReportMissingArg(cx, args.calleev(), 0);
+        return false;
+    }
+
+    bool keyonly = false;
+    if (args.length() >= 2)
+        keyonly = js_ValueToBoolean(args[1]);
     unsigned flags = JSITER_OWNONLY | (keyonly ? 0 : (JSITER_FOREACH | JSITER_KEYVALUE));
-    *vp = argc >= 1 ? argv[0] : UndefinedValue();
-    return ValueToIterator(cx, flags, vp);
+
+    if (!ValueToIterator(cx, flags, &args[0]))
+        return false;
+    args.rval() = args[0];
+    return true;
 }
 
 JSBool