Assertion failure: containingBlockWidth >= 0, at layout/generic/nsFrame.cpp:4620

fyi, Bughunter sees this on http://www.kasa.cz/udirna-rulyt-zahradni-mala-nahradni-obal-silne-deformovany-obal-2000014126/

and now https://support.skype.com/ar/faq/FA12097/dlyl-jwdt-almkalmat-sth-mktb-windows?intsrc=client-_-windows-_-7.14-_-go-help.guides.soundsetupguide

david is this something for you, or do you know who could take a look at this ?

example url from bughunter was http://altapress.ru/story/168911?photo=6#gallery

Perhaps Mats (who added the assertion) can look. (Though I was going to suggest Mats even before checking that he added it...)

The crashtest here appears to be permafailing on Aurora since the uplift today. https://treeherder.mozilla.org/logviewer.html#?job_id=2096724&repo=mozilla-aurora The two we're hitting are: ###!!! ASSERTION: Can't solve for both start and end: 'NS_AUTOOFFSET != offsets.IEnd(outerWM)', file /builds/slave/m-aurora-and-api-15-d-00000000/build/src/layout/generic/nsAbsoluteContainingBlock.cpp, line 448 ###!!! ASSERTION: unexpected max block size: 'aBSize >= 0', file /builds/slave/m-aurora-and-api-15-d-00000000/build/src/layout/generic/nsFloatManager.cpp, line 128 Mats, is this safe to annotate away or did you want to take a look?

The code after those assertions looks safe regardless of values, so please annotate. Thanks.

I've updated the expectations on aurora with https://hg.mozilla.org/releases/mozilla-aurora/rev/9a446438d3a4 I imagine we'll want to land something similar to trunk so we don't hit this every merge going forward, but it's still asserting four times on trunk. Would we want to change it to (Android,2-4) (!Android,4) to cover everything?

Sure. Or just 2-4 for all platforms.

Landed https://hg.mozilla.org/integration/mozilla-inbound/rev/6312f4020b6d to inbound to fix this going forward.