1406111 - stylo: File operations buttons from Google Drive are flickering while hovering over them

Status: VERIFIED FIXED

(Core :: CSS Parsing and Computation, defect, P2)

Description

[Cristina Badescu [:cbadescu], Experiments QA]

Attachment: Screen Recording(1).mov

[Steps to reproduce]
 1. Start the latest Nightly build 58.0a1 (Build ID: 20171005100211) with a clean profile.
 2. Navigate to https://drive.google.com and log in with a valid account, that has stored files in it.
 3. Select one document and hover over the file operations buttons located in the top right side above the files list.
 4. Observe the hover animation behavior.
 
[Expected results]
- The buttons hover animation is correctly displayed.
 
 [Actual results]
- The buttons hover animation flickers.

[Notes]
- Attached a screen recording of the issue.

[Regression]
- This issue is not reproducible on latest Firefox Release 56.0. I've managed to find the regression window. 
Here are the results:
Last good revision: a1903b0f0ead5b2952dd4a1b6a41b20a65a07f44
First bad revision: cde998ffc14f8a14be13713f78625b182ee97b7c
Pushlog: https://goo.gl/bxVSsA

From the pushlog, it seems that the bug 18604 has caused this. Emilio, can you please take a look?

Comment 1

[Emilio Cobos Álvarez (:emilio)]

Yup, I think I know what's going on, let me just confirm it.

Comment 2

[Emilio Cobos Álvarez (:emilio)]

Attachment: Patch

(Not sure who of both is the best reviewer).

Also, need to write a test, but not sure the best test to test our animation infra. Any pointers would be helpful.

Comment 3

[Hiroyuki Ikezoe (:hiro)]

https://hg.mozilla.org/mozilla-central/rev/8f6d5b585d09

Comment 4

[Cristina Badescu [:cbadescu], Experiments QA]

I can confirm that this issue is no longer reproducible on the latest Nightly build 58.0a1 (2017-10-09), on Windows 10 x64, Mac 10.12 and Ubuntu 14.04 x64.