Bugzilla

This bug is for crash report bp-8440ef13-d122-46d4-a2a2-43b2e0200720.

Top 10 frames of crashing thread:
```
0 XUL nsPrintJob::ReflowPrintObject layout/printing/nsPrintJob.cpp:2003
1 XUL nsPrintJob::ReflowDocList layout/printing/nsPrintJob.cpp:1648
2 XUL nsPrintJob::InitPrintDocConstruction layout/printing/nsPrintJob.cpp:1674
3 XUL nsPrintJob::Observe layout/printing/nsPrintJob.cpp:2907
4 XUL mozilla::embedding::PrintProgressDialogChild::RecvDialogOpened toolkit/components/printingui/ipc/PrintProgressDialogChild.cpp:37
5 XUL mozilla::embedding::PPrintProgressDialogChild::OnMessageReceived ipc/ipdl/PPrintProgressDialogChild.cpp:228
6 XUL mozilla::dom::PContentChild::OnMessageReceived ipc/ipdl/PContentChild.cpp:8424
7 XUL mozilla::ipc::MessageChannel::DispatchMessage ipc/glue/MessageChannel.cpp:2150
8 XUL mozilla::ipc::MessageChannel::MessageTask::Run ipc/glue/MessageChannel.cpp:1953
9 XUL mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal xpcom/threads/TaskController.cpp:242
```
Encountered this tab crash while printing a file on macOS 10.14. The "Print selection Only" option was unlocked even if no selection was performed on the page. Selecting the option and performing the print leads to tab crash.

I will investigate this behavior and will come back with a detailed description asap.

This bug is for crash report bp-8440ef13-d122-46d4-a2a2-43b2e0200720.

Top 10 frames of crashing thread:
```
0 XUL nsPrintJob::ReflowPrintObject layout/printing/nsPrintJob.cpp:2003
1 XUL nsPrintJob::ReflowDocList layout/printing/nsPrintJob.cpp:1648
2 XUL nsPrintJob::InitPrintDocConstruction layout/printing/nsPrintJob.cpp:1674
3 XUL nsPrintJob::Observe layout/printing/nsPrintJob.cpp:2907
4 XUL mozilla::embedding::PrintProgressDialogChild::RecvDialogOpened toolkit/components/printingui/ipc/PrintProgressDialogChild.cpp:37
5 XUL mozilla::embedding::PPrintProgressDialogChild::OnMessageReceived ipc/ipdl/PPrintProgressDialogChild.cpp:228
6 XUL mozilla::dom::PContentChild::OnMessageReceived ipc/ipdl/PContentChild.cpp:8424
7 XUL mozilla::ipc::MessageChannel::DispatchMessage ipc/glue/MessageChannel.cpp:2150
8 XUL mozilla::ipc::MessageChannel::MessageTask::Run ipc/glue/MessageChannel.cpp:1953
9 XUL mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal xpcom/threads/TaskController.cpp:242
```
It seems that trying to print a specific xml element selection leads to tab crash

**Affected versions**
* 80.0a1 (BuildId:20200720094507)
* 79.0b9 (BuildId:20200717001501)
* 78.0.2 (BuilId:20200708170202)
* 68.10.0esr (BuildId:20200622191537)
* 78.0.2esr (BuildId:20200708170510)

**Affected platforms**
* Windows 10 64bit
* Ubuntu 18.04 64bit
* macOS 10.14

**Steps to reproduce**
1. Launch Firefox.
2. Access the following [link](https://www.w3schools.com/xml/cd_catalog.xml).
3. Select <COUNTRY>USA</COUNTRY>
4. Hit CTRL+P or CMD+P (on macOS)
5. Select the “Selection” on Windows or “Print Selection Only” option on macOS.
6. Click the Ok/Print button.


**Expected result**
*  Firefox is stable and the selection is successfully printed.

**Actual result**
* Tab Crash.

**Regression Range**
* This seems to be an old regression:
* Pushlog: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=c2248f85346939d3e0b01f57276c440ccb2d16a1&tochange=18a9cb5cb32d0e8031d0a80901b199d5e9827d83
* Possible Regressor: Since this is reproducible on older builds, unfortunately, mozregression keeps skipping builds.