Triple click line selection in Firefox

[manstie]

How to reproduce:

1. Open http://edg2s.github.io/rangefix/ in Firefox 82.0.2
2. Triple click to select the whole line with the example image
3. 

[edg2s]

Thanks. It looks like with triple click on FF the range becomes [<p> ... </p>] (start/end node: p, offsets: [0,2]), whereas on Chrome, triple click stills selects inside text nodes: <p>[ ... ]</p>.

Setting this programmatically in Chrome gives incorrect rectangles:

I would say this is a bug in both browsers, although clearly more problematic in FF.

[edg2s]

The cause of this bug appears to be the display: inline-block <img> which is wrapped in an display: inline <u>. If i remove the inline wrapper, everything works fine in all browsers:

[edg2s]

Upstream bugs:
Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=1147474
Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1676467

[edg2s]

According to a comment on the Firefox task, this is behaving according to specification:

So spec is in https://drafts.csswg.org/cssom-view-1/#dom-range-getclientrects:

For each element selected by the range, whose parent is not selected by the range, include the border areas returned by invoking getClientRects() on the element.

So it seems to me that if <u> is selected by the range completely, then we'd return an smaller rect than if it wasn't per the above definition (because when <u> is not fully selected, then we union the getClientRects() of the text and the image, instead of just returning the rects of the <u>). That seems unfortunate, though it's what the spec seems to call for.