https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/installedapp/RelatedApplication.idl

RelatedApplication is defined as:
interface RelatedApplication {
    readonly attribute DOMString platform;
    readonly attribute DOMString url;
    readonly attribute DOMString id;
};

There is really no reason for this to be an interface; it can just be a simple dictionary (like ShareData).

I tried converting it and it was a big deal (the code that binds to it needs to completely change and there are garbage collector ramifications). Still, this should be changed before it is spec'd.

In the mean time, I think we can add [NoInterfaceObject] to remove the presence of the top-level interface object RelatedApplication.

Note: The current implementation is impossible to idlharness-test due to Issue 643712. That isn't a good reason to change it, but I think changing it (for other reasons) will work around that.