Resize Observer.widl

enum ResizeObserverBoxOptions {
    "border-box", "content-box", "device-pixel-content-box"
};

dictionary ResizeObserverOptions {
    ResizeObserverBoxOptions box = "content-box";
};

[Exposed=(Window),
 Constructor(ResizeObserverCallback callback)]
interface ResizeObserver {
    void observe(Element target, optional ResizeObserverOptions options);
    void unobserve(Element target);
    void disconnect();
};

callback ResizeObserverCallback = void (FrozenArray<ResizeObserverEntry> entries, ResizeObserver observer);

[Exposed=Window]
interface ResizeObserverEntry {
    readonly attribute Element target;
    readonly attribute DOMRectReadOnly contentRect;
    readonly attribute sequence<ResizeObserverSize> borderBoxSize;
    readonly attribute sequence<ResizeObserverSize> contentBoxSize;
    readonly attribute sequence<ResizeObserverSize> devicePixelContentBoxSize;
};

interface ResizeObserverSize {
    readonly attribute unrestricted double inlineSize;
    readonly attribute unrestricted double blockSize;
};

[Constructor(Element target)
]
interface ResizeObservation {
    readonly attribute Element target;
    readonly attribute ResizeObserverBoxOptions observedBox;
    readonly attribute sequence<ResizeObserverSize> lastReportedSizes;
};