(In reply to David Burns :automatedtester from comment #0)

/css/css-backgrounds/background-size-001.html

I filed bug 1560198 on this.

/css/css-backgrounds/background-size-031.html

This one did fail as shown in this run from the foolip.io page:
https://wpt.fyi/results/css/css-backgrounds/background-size-031.html?run_id=4902590919737344&run_id=4865981792911360&run_id=6019805698064384

But if I view the comparison without "run_id", I see that Firefox passes the test:
https://wpt.fyi/results/css/css-backgrounds/background-size-031.html

So maybe this one has been fixed.

(In reply to David Burns :automatedtester from comment #0)

Firefox only failures for web platform tests as documented in
https://foolip.github.io/ad-hoc-wpt-results-analysis/firefox-lone-failures.
html

/css/css-backgrounds/background-attachment-local/attachment-local-clipping-color-3.html

As for background-size-031.html, this one passes now.

/css/css-backgrounds/background-attachment-local/attachment-local-clipping-image-1.html
/css/css-backgrounds/background-attachment-local/attachment-local-clipping-image-2.html
/css/css-backgrounds/background-attachment-local/attachment-local-clipping-image-3.html

These are subtle fuzzy mismatches, which we should perhaps just annotate as fuzzy (or adjust the test to use Ahem, perhaps). I filed bug 1560210 on addressing these.

/css/css-backgrounds/background-attachment-local/attachment-local-positioning-2.html
/css/css-backgrounds/background-attachment-local/attachment-local-positioning-5.html
/css/css-backgrounds/background-attachment-local/attachment-scroll-positioning-1.html
/css/css-backgrounds/background-origin-006.html
/css/css-backgrounds/background-repeat/background-repeat-repeat-x.xht
/css/css-backgrounds/background-repeat/background-repeat-repeat-y.xht

These all pass now, too. e.g. here's the last one:
https://wpt.fyi/results/css/css-backgrounds/background-repeat/background-repeat-repeat-y.xht

That (and comment 1) covers all of the tests listed in comment 0. Also, foolip's list now includes the following tests not listed in comment 0:

• https://wpt.fyi/results/css/css-backgrounds/background-image-first-line.html (which is a test bug that I'm addressing in bug 1560205)
• https://wpt.fyi/results/css/css-backgrounds/child-move-reveals-parent-background.html (which passes now)
• https://wpt.fyi/results/css/css-backgrounds/table-cell-background-local.html (which uses overflow:hidden on a table cell, and is likely broken due to bug 221154)

• https://wpt.fyi/results/css/css-backgrounds/table-cell-background-local.html (which uses overflow:hidden on a table cell, and is likely broken due to bug 221154)

I reached exactly the same conclusion. If/when bug 221154 gets fixed, then chances are Firefox will pass
http://wpt.live/css/css-backgrounds/table-cell-background-local.html