JS_UNLOCK_RUNTIME(rt);
if (unlocked) JS_UNLOCK_GC(rt);
js_ContextIterator(JSRuntime *rt, JSContext **iterp){    JSContext *cx = *iterp;    JS_LOCK_RUNTIME(rt);    if (!cx)        cx = (JSContext *)&rt->contextList;    cx = (JSContext *)cx->links.next;    if (&cx->links == &rt->contextList)        cx = NULL;    *iterp = cx;    JS_UNLOCK_RUNTIME(rt);    return cx;}