When generated content is created, we need to eagerly style it. Not doing this is the cause of layout/reftests/bugs/451168-1.html tripping the bug 1345695 assertion.

Comment on attachment 8849891 [details] Bug 1349457 - stylo: Eagerly style generated content. https://reviewboard.mozilla.org/r/122636/#review125012 r=me with the |createdGeneratedContent| stuff removed, or a good reason why we should keep it. ::: layout/base/nsCSSFrameConstructor.cpp:1918 (Diff revision 2) > + if (createdGeneratedContent && aParentContent->IsStyledByServo()) { > + mPresShell->StyleSet()->AsServo()->StyleNewSubtree(container); > + } Hm, shouldn't we style |container| unconditionally? I don't understand what case we're trying to optimize for with |createdGeneratedContent| and why it would be ok to skip |container| even if |createdGeneratedContent| were false.

Note that I'm assuming here that we only end up in this function if we are very likely to create actual generated content. Otherwise we'd be appending a lot of unnecessary XUL NAC to the DOM.

You are right that we get in here only if we have ::before/::after rules that could produce generated content. It is possible for nsCSSFrameConstructor::CreateGeneratedContent to return null, either (a) if the |content: url()| didn't resolve to an image, or (b) the |content: attr(x)| didn't refer to an existing attribute on the element. I assume such cases are rare, so we could style |container| unconditionally if you think it's not worth checking whether CreateGeneratedContent succeeded.

Yeah, let's keep it simple and unconditional.

Pushed by cmccormack@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/0c15ca7e1ba7 stylo: Eagerly style generated content. r=bholley