This is part of the cleanup I want to do before doing bug 1476281.

Using references helps to see when stuff can and cannot be null. I removed useless aTag / aNamespaceId arguments which are useless now that XBL can't override them (bug 1450617), so FindXULData is the only one that keeps them alive. Also, I took the liberty of renaming a few fooComputedStyle variables to just fooStyle, and clarify naming in some pseudo-element-related functions to say originating element (the spec term) and avoid confusing it with the generated _moz_generated_content_before / _moz_generated_content_after element. Note that this is a partial state, more stuff will come in the future.

It's not needed anymore, since we tag the pseudo-elements at creation time for styling.

It's the same, and avoids a bit of duplication.

We verify the flattened tree is correct in VerifyFlatTree (in RestyleManager), plus the post-condition still holds of course.

Comment on attachment 8994572 [details] Trivial frame constructor cleanup. Ting-Yu Lin [:TYLin] (UTC-7) has approved the revision. https://phabricator.services.mozilla.com/D2326

Comment on attachment 8994605 [details] Bug 1478069: Use AddFrameConstructionItems for display: contents. Ting-Yu Lin [:TYLin] (UTC-7) has approved the revision. https://phabricator.services.mozilla.com/D2329

Comment on attachment 8994607 [details] Bug 1478069: Remove useless ping-pong between flattened and light child. Ting-Yu Lin [:TYLin] (UTC-7) has approved the revision. https://phabricator.services.mozilla.com/D2331

Comment on attachment 8994601 [details] Bug 1478069: Remove ContentInfo::mChildren. Boris Zbarsky [:bz] (no decent commit message means r-) has approved the revision. https://phabricator.services.mozilla.com/D2330

Pushed by emilio@crisal.io: https://hg.mozilla.org/integration/mozilla-inbound/rev/94f84afc3c6d Trivial frame constructor cleanup. r=TYLin https://hg.mozilla.org/integration/mozilla-inbound/rev/3c73ab776d8b Remove useless ping-pong between flattened and light child. r=TYLin https://hg.mozilla.org/integration/mozilla-inbound/rev/5ef482c2a889 Use AddFrameConstructionItems for display: contents. r=TYLin https://hg.mozilla.org/integration/mozilla-inbound/rev/717970e42f16 Remove ContentInfo::mChildren. r=bz

https://hg.mozilla.org/mozilla-central/rev/94f84afc3c6d https://hg.mozilla.org/mozilla-central/rev/3c73ab776d8b https://hg.mozilla.org/mozilla-central/rev/5ef482c2a889 https://hg.mozilla.org/mozilla-central/rev/717970e42f16