High Resolution Time IDL tests
[PrimaryGlobal]
interface Window {
};
[Exposed=Worker]
interface WorkerGlobalScope {
};
[Exposed=(Window,Worker)]
interface EventTarget {
};
typedef double DOMHighResTimeStamp;
[Exposed=(Window,Worker)]
interface Performance : EventTarget {
    DOMHighResTimeStamp now();
    serializer = {attribute};
};
[NoInterfaceObject,
 Exposed=(Window,Worker)]
interface GlobalPerformance {
    [Replaceable]
    readonly attribute Performance performance;
};
Window implements GlobalPerformance;
WorkerGlobalScope implements GlobalPerformance;