Able to reproduce the issue on Windows 10,Windows-7,Ubuntu 14.04 and Mac 10.12.3 with Chrome stable version 57.0.2987.133 and Canary #59.0.3060.0 
This is a non regression issue, observed from M30# 30.0.1550.0 and marking it as untriaged to get more inputs from dev team.
Please find attached screen cast for reference.

Thanks..

Deleted: 707533.mp4 167 KB

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Let's make sure we get this right in NG.

By the way, the last test is not good because it seems Chromium does not support display:ruby yet, so it behaves like display:block.

It should be as follows (which still fails):

  <div><ruby>Hello<br />Goodbye</ruby> etcetera</div>

rune@, meade@, could you mind to advise?

This issue doesn't require atomic inline. Layout picks first line style if first line as you know, but when the first line has descendants, we don't inherit from the first line style.

Test:
http://output.jsbin.com/vihufa/

What are the best way to solve this?

That seemed a different issue to me, so I filed it in https://bugs.chromium.org/p/chromium/issues/detail?id=708783

Rune, you've been looking at first-line lately, do you mind taking a look? Thanks!

Not much relevant, but CSS Display was fixed, it no longer says that ruby containers are atomic inlines.
So the problem is that ::first-line skips atomic inlines and ruby containers.

+eae@, +ikilpatrick@ as this might affect NG tree building.

More tests: http://output.jsbin.com/vihufa/

I think what we should do for ::first-line in NG is that:

1. During the tree building, we create two boxes, one for ::first-line and the rest of line.
2. The ::first-line box has constraint_space to contain single line, the height of which is determined at layout time.
3. The box for the rest of line continues from the break token of the ::first-line box.

I'm not sure how efficiently we can calc style by creating two boxes, but this looks similar to regular overflow/fragmentation.

::first-line style is never inherited into atomic inlines because of the test here:

https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/layout/LayoutBlockFlowLine.cpp?q=LayoutBlockFlow::+package:%5Echromium$&dr=CSs&l=1984

as UpdateAlwaysCreateLineBoxes() call in the else statement is the only path which queries first-line or inherited first-line styles.

Some info from Francois on how Edge works:
https://github.com/w3c/csswg-drafts/issues/1097#issuecomment-294630127
followed by dabaron's comment on Gecko's info.

From the test in #10, we don't inherit even into <span>s. Querying the correct style as Rune pointed out is one problem, inheriting from first-line style is another problem IIUC.

Since #10 looks too inefficient to me, I might need to study more on how Edge and Gecko handles first-line.

 Issue 750268  has been merged into this issue.

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