Chrome Version: 72.0.3610.2 (Official Build) dev (64-bit)
OS: (e.g. Win10, MacOS 10.12, etc...)

What steps will reproduce the problem?
(1) load testcase: https://jsfiddle.net/1dau69bn/

What is the expected result?
The teal border-bottom edges should all be aligned.
(The boxes should suppress their "real" baselines, since they have 'contain:layout', and they should instead synthesize a baseline from their border-bottom edge, and they should do baseline alignment using that synthesized baseline.)

What happens instead?
The boxes for "block", "fieldset", and "multi col" are too low -- they're aligning with their contents' actual baselines.  They're not honoring the spec text about 'contain:layout'.

Firefox Nightly (with about:config pref layout.css.contain.enabled = true) gives the "expected result" here, thanks to :rego's work in https://bugzilla.mozilla.org/show_bug.cgi?id=1491235 .  Note also that I'll be adding a version of the above jsfiddle as a web platform test (indirectly, via mozilla's auto-synchronized w3c-css/submitted directory) over in https://bugzilla.mozilla.org/show_bug.cgi?id=1507663


Spec quote for "contain:layout" behavior:
====
7. For the purpose of the vertical-align property, or any other property whose effects need to relate the position of the containing element’s baseline to something other than its descendants, the containing element is treated as having no baseline.
====
https://drafts.csswg.org/css-contain/#containment-layout

Spec quote for what "treated as having no baseline" means in this context (for flex items):
===
If the item does not have a baseline in the necessary axis, then one is synthesized from the flex item’s border box.
===
https://drafts.csswg.org/css-flexbox-1/#valdef-align-items-baseline