Why can't I expand this event object in the chrome console?

Why can't I expand this event object in the chrome console?

Simplified, what I'm doing is running this in the console:
window.onbeforeunload = function (e) {
var e = e || window.event;
if (e) {
console.log(e);
}
}
But in the console, when the event fires (by trying to "leave page" in the
middle of writing an SO question) what I see is this:
Event {clipboardData: undefined, cancelBubble: false, returnValue: true,
srcElement: document, defaultPrevented: false…}
With a little "i" graphic next to it. When I click the arrow next to it to
expand the object in the console, nothing happens. The arrow turns to
indicate that it has expanded, but it doesn't expand.
What am I missing here??