What should happen when clicking on the edge of an <area> shape?

[zcorpan]

https://html.spec.whatwg.org/multipage/embedded-content.html#processing-model

Now, the shape represented by the element is the one described for the entry in the list below corresponding to the state of the shape attribute:​

@fsoder found in https://critic.hoppipolla.co.uk/showcomment?chain=12553 that the spec doesn't really say what should happen if one clicks at a coordinate that is on the edge or intersection of a shape.

Example: http://software.hixie.ch/utilities/js/live-dom-viewer/saved/3837