[Bug 20225] don't allow overridden operations and attribute getters/setters to be invoked on descendant objects

https://www.w3.org/Bugs/Public/show_bug.cgi?id=20225

--- Comment #4 from Boris Zbarsky <bzbarsky@mit.edu> ---
> So HTMLCollection.prototype.namedItem would always first just check if `this`
> is an HTMLPropertiesCollection, and throw if so.

Yes, that's runtime introspection, no?  Depending on exactly what the sub-set
of interfaces that override the property is this could get pretty expensive...

I suppose we could try it in practice and see how much it hurts things, but the
check above would about double the cost of calling namedItem on
HTMLCollections.

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Received on Tuesday, 4 December 2012 01:39:04 UTC