Bugzilla

Here's a further-reduced testcase, which just uses an `inline-block`, and which reproduces the bug.

This demonstrates that the requirements described in comment 11 aren't actually requirements -- this is broken whenever the fragmentation-ballback codepath is triggered (for actual printed/printed-to-PDF output, not for print-preview).

This was already-broken at the time that we landed the fragmentation-fallback codepath (in bug 1640197), but I think we didn't notice at the time because print-preview looked correct.  But I just confirmed that this was even broken back then, using [testcase #3](https://bugzilla.mozilla.org/attachment.cgi?id=9179658) from that bug, with Nightly 2020-10-29 and `layout.display-list.improve-fragmentation` set to `true`, printing to PDF.

Here's a further-reduced testcase, which just uses an `inline-block`, and which reproduces the bug.

This demonstrates that the requirements described in comment 11 (display:flex/grid and nondefault overflow on body) aren't actually strict requirements -- this is unfortunately broken **whenever the fragmentation-ballback codepath is triggered** (for actual printed/printed-to-PDF output, not for print-preview).

This was already-broken at the time that we landed the fragmentation-fallback codepath (in bug 1640197), but I think we didn't notice at the time because print-preview looked correct.  But I just confirmed that this was even broken back then, using [testcase #3](https://bugzilla.mozilla.org/attachment.cgi?id=9179658) from that bug, with Nightly 2020-10-29 and `layout.display-list.improve-fragmentation` set to `true`, printing to PDF.

Here's a further-reduced testcase, which just uses an `inline-block`, and which reproduces the bug.

This demonstrates that the requirements described in comment 11 (display:flex/grid and nondefault overflow on body) aren't actually strict requirements -- this is unfortunately broken **whenever the fragmentation-ballback codepath is triggered** (for actual printed/printed-to-PDF output, not for print-preview).

Also, I confirmed that this was already-broken at the time that we landed the fragmentation-fallback codepath (in bug 1640197), but I think we didn't notice at the time because print-preview looked correct.  But I just confirmed that this was even broken back then, using [testcase #3](https://bugzilla.mozilla.org/attachment.cgi?id=9179658) from that bug, with Nightly 2020-10-29 and `layout.display-list.improve-fragmentation` set to `true`, printing to PDF.