Crash report: https://crash-stats.mozilla.org/report/index/837d377b-7f66-4855-8383-4138d0200927

Top 10 frames of crashing thread:

0 xul.dll webrender::scene_building::SceneBuilder::process_common_properties gfx/wr/webrender/src/scene_building.rs:763
1 xul.dll webrender::scene_building::SceneBuilder::build_item gfx/wr/webrender/src/scene_building.rs:916
2 xul.dll webrender::scene_building::SceneBuilder::build_item gfx/wr/webrender/src/scene_building.rs:916
3 xul.dll tan 
4 xul.dll tan 
5 mozglue.dll memmove 
6 xul.dll webrender::clip::ClipStore::register_clip_template gfx/wr/webrender/src/clip.rs:960
7 xul.dll webrender::clip::ClipStore::register_clip_template gfx/wr/webrender/src/clip.rs:960
8 xul.dll webrender::scene_building::create_prim_instance gfx/wr/webrender/src/scene_building.rs:3597
9 xul.dll webrender::scene_building::create_prim_instance gfx/wr/webrender/src/scene_building.rs:3597

This is an Windows/AArch64 crash, it does not seem to occur on x86. The crash appears to be a NULL-pointer dereference but that doesn't seem possible given that it's happening in Rust code. The stack is of poor quality due to the lack of unwinding information (see bug 1529355). The first instance of this crash is for buildid 20200922154306.

Pushlogs for the first builds, and two prior:

https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=726dc76332b4&tochange=81d47e62000723a24bb20f1abdda51cfc62c553f
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a5cdfde00f15&tochange=726dc76332b4ffd8a44429a51f98a16a3e1a2940
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=ddd533d95b74&tochange=a5cdfde00f159276453541049a8cbb5f7043ae2a

Doesn't look to be anything too excited WebRender / scene building wise.

Closing because no crashes reported for 12 weeks.