Crash report: https://crash-stats.mozilla.org/report/index/b365790f-9d07-44e3-bdc8-585060200916

Top 10 frames of crashing thread:

0 libxul.so mozilla::dom::ScriptLoadRequest::MaybeCancelOffThreadScript dom/script/ScriptLoadRequest.cpp:158
1 libxul.so mozilla::dom::ScriptLoadRequest::~ScriptLoadRequest dom/script/ScriptLoadRequest.cpp:117
2 libxul.so mozilla::dom::ScriptLoadRequest::~ScriptLoadRequest dom/script/ScriptLoadRequest.cpp:108
3 libxul.so void nsPurpleBuffer::VisitEntries<SnowWhiteKiller> xpcom/base/nsCycleCollector.cpp:942
4 libxul.so nsCycleCollector_doDeferredDeletionWithBudget xpcom/base/nsCycleCollector.cpp:3889
5 libxul.so AsyncFreeSnowWhite::Run js/xpconnect/src/XPCJSRuntime.cpp:154
6 libxul.so IdleRunnableWrapper::Run xpcom/threads/nsThreadUtils.cpp:348
7 libxul.so mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal xpcom/threads/TaskController.cpp:514
8 libxul.so nsThread::ProcessNextEvent xpcom/threads/nsThread.cpp:1234
9 libxul.so mozilla::ipc::MessagePump::Run ipc/glue/MessagePump.cpp:87

This seems to be a new kind of crash in Nightly, looks like bug 1652126 introduces it. There are not a lot of crashes, however it does crash on multiple platforms from various installations.

They seem like a real crash, not something caused by bad memory bits.

I think the problem here may be that I need to clear aRequest->mRunnable if the user goes OOM while trying to off thread compile.

https://hg.mozilla.org/mozilla-central/rev/484f95173d20