[webidl] Error Processing should talk about when to use default values for attributes (#92)

The current https://svgwg.org/svg2-draft/implnote.html#ErrorProcessing section doesn't refer to initial/invalid values of attributes, so it's not exactly clear that you're meant to use them when an attribute is invalid in some way.  For example looking at https://svgwg.org/svg2-draft/coords.html#ViewBoxAttribute it says that negative values for width/height inside the viewBox are an error, but the Error Processing section linked to doesn't make it clear that the behaviour should be as if the attribute weren't specified (as that's what's specified for the "initial value" in the grey attribute definition box).

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Reply to this email directly or view it on GitHub:
https://github.com/heycam/webidl/issues/92