Bug 101101 – [chromium][CSS Regions] fast/regions/autoheight-definedheight-changenotdetected.html fails on MacOS 10.8

• Component: Layout and Rendering
• Status: RESOLVED WONTFIX

[Stephen White]

This reftest doesn't work on MacOS 10.8:

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=fast%2Fregions%2Fautoheight-definedheight-changenotdetected.html

[Mihnea Ovidenie]

Already taken a look without being able to reproduce it, but i may have a potential fix for it.

[Mihnea Ovidenie]

Created attachment 172226 [details]
Patch

I suspect turning off font-smoothing for the Ahem font used for content that is flowed into regions will fix the problem. I was not able to reproduce the problem on my ML machine.

[Ryosuke Niwa]

Comment on attachment 172226 [details]
Patch

I'm a bit skeptical but let's try that.

[Ryosuke Niwa]

Comment on attachment 172226 [details]
Patch

Looking at the actual result more closely, this might be a real bug in Chromium. Let's hold off on landing this.
http://build.chromium.org/f/chromium/layout_test_results/WebKit_Mac10_8/results/layout-test-results/fast/regions/autoheight-definedheight-changenotdetected-actual.png

[Ryosuke Niwa]

Emil & Levi,

Is 1px anti-aliasing showing up on the boxes on the left and the bottom right expected? I can't help but think that this is a real bug in Chromium on 10.8.

[Emil A Eklund]

(In reply to comment #5)
> Emil & Levi,
> 
> Is 1px anti-aliasing showing up on the boxes on the left and the bottom right expected? I can't help but think that this is a real bug in Chromium on 10.8.

Depends on what the test is doing, hard to tell from the screenshot.

[Mihnea Ovidenie]

(In reply to comment #6)
> (In reply to comment #5)
> > Emil & Levi,
> > 
> > Is 1px anti-aliasing showing up on the boxes on the left and the bottom right expected? I can't help but think that this is a real bug in Chromium on 10.8.
> 
> Depends on what the test is doing, hard to tell from the screenshot.

The test is using a 50px Ahem to create a green line. Independent of regions, i have noticed that a simple div using a 50px Ahem font has the same antialiasing, which is gone if one specifies -webkit-font-smoothing: none, hence my proposed fix for the test in Chromium.