Description:
Print preview is showing layout/rendering issues

Steps to reproduce

-Go to https://es.wikipedia.org/wiki/Argentina
-go to hamburger menu > Print the page
-Print preview shows rendering layout issues on almost all pages

Actual Result
Rendering layout issues are showing up on almost all pages

Expected Result
No visual problems should appear

Tested on:

Windows10 64bit:
FF Nightly 71.0a1 reproducible
FF Beta 70.0b6 not reproducible
FF Release 69 not reproducible

Ubuntu 18.04 64bit
FF Nightly 71.0a1 not reproducible
FF Beta 70.0b6 not reproducible
FF Release 69 not reproducible

MacOs:There was no print preview

Mozregression:

build_date: 2019-09-10 19:26:16.877000
build_url: https://queue.taskcluster.net/v1/task/Vl45MGxUTDKAuvXyQqI-eg/runs/0/artifacts/public%2Fbuild%2Ftarget.zip
changeset: c044e1acf814933d7138d5848f8c9f7fce6cac83
pushlog_url: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=0e0e9c22321ed9f284744cfeb3507710b2d5d606&tochange=c044e1acf814933d7138d5848f8c9f7fce6cac83

FWIW I was able to reproduce this issue on Fedora 30, so I don't believe it is platform specific.

The issue appears to be that the header text for the document (such as page title) is rendered stretched over the document. Scrolling up & down the document causes the rendering of this text to change shape after I move it off screen & scroll back to it. It appears as though it is be caused by something nondeterministic.

I don't remember testing whether this is attached to webrender specifically or not.

:jrmuizel, I think this is probably caused by your changes, based on the pushlog.

I suspect this has the same root cause as bug 1580922

Given comment 1 and comment 2, it sounds like we should move this the the WR component (or at least somewhere on the gfx team radar).

Appears to be fixed.