1297572 - AllChildrenIterator misses native anonymous content from the root scroll frame

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

[Bobby Holley (:bholley)]

It detects native anonymous children by QueryFrame-ing the primary frame to nsINativeAnonymousContentCreator. This generally works, but the root scroll frame is not the primary frame of the root element, and so we miss this case. This is problematic for stylo, since we restyle using the DOM rather than the frame tree, so we need our DOM iterator to handle corner cases like this.

I have a patch which I'll run through try.

Comment 1

[Bobby Holley (:bholley)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=879f5dcad103

Comment 2

[Bobby Holley (:bholley)]

Attachment: Handle the root scroll frame in AllChildrenIterator. v1

Comment 3

[Cameron McCormack (:heycam)]

Comment on attachment 8784472 [details] [diff] [review]
Handle the root scroll frame in AllChildrenIterator. v1

Review of attachment 8784472 [details] [diff] [review]:
-----------------------------------------------------------------

r=me with that fixed.

::: dom/base/ChildIterator.cpp
@@ +423,5 @@
> +        nsIPresShell* presShell = mOriginalContent->OwnerDoc()->GetShell();
> +        nsIFrame* scrollFrame = presShell ? presShell->GetRootScrollFrame() : nullptr;
> +        if (scrollFrame) {
> +          AppendAnonymousChildrenFromFrame(scrollFrame);
> +        }

Don't we need to do this all in GetPreviousChild too?

Comment 4

[Bobby Holley (:bholley)]

Attachment: Part 0 - Prevent HasPseudoElementData from erroneously tracking anonymous

boxes. r=heycam

The layout inspector ends up traversing into the root scroll frame in the next patch. If we don't
fix this, we erroneously enter this code here:

http://searchfox.org/mozilla-central/rev/44f6964ba95b8ddd8ebf70c55b34cd2323afeef4/layout/style/nsComputedDOMStyle.cpp#682

in this test:

devtools/client/inspector/markup/test/browser_markup_anonymous_04.js

Comment 5

[Bobby Holley (:bholley)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=2b0f2c56f633

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/e6a1ddda457e
Prevent HasPseudoElementData from erroneously tracking anonymous boxes. r=heycam
https://hg.mozilla.org/integration/mozilla-inbound/rev/6789cc1bb12a
Handle the root scroll frame in AllChildrenIterator. r=heycam

Comment 7

[Cameron McCormack (:heycam)]

FWIW I just pushed a try run to check that we never have non-pseudo style inheriting from anon box style, except for the viewport scroll case, and I didn't get any failures.

https://treeherder.mozilla.org/#/jobs?repo=try&revision=f0d6f94673ac

Comment 8

[Bobby Holley (:bholley)]

Thanks! When I get around to it, I'll see if I can push a patch to try to make the root scroll NAC inherit null instead of the anon boxes.

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/e6a1ddda457e
https://hg.mozilla.org/mozilla-central/rev/6789cc1bb12a