UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce the problem:
1. Enable 'Experimental Web Platform features' in chrome://flags
2. Relaunch Chromium 
3. Open https://test.csswg.org/harness/test/css-rhythm-1_dev/single/line-height-step-valign-001/format/html5/

What is the expected behavior?
This two line should same exactly.

What went wrong?
The fourth and fifth 'X' are different in these two lines. I attached the screenshot, please see the attachment.

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 59.0.3055.0  Channel: n/a
OS Version: OS X 10.12.4
Flash Version:
 

Deleted: Screen Shot 2017-03-28 at 16.30.11.png 362 KB

	Screen Shot 2017-03-28 at 16.30.11.png 362 KB View Download