Looks like updating incubator pulled in bug 1241867, which broke stylo. CI can't come soon enough.

Stack: Assertion failure: nsContentUtils::IsSafeToRunScript(), at /files/mozilla/repos/qq/layout/base/nsPresContext.cpp:1903 #01: nsPresContext::MediaFeatureValuesChanged(nsRestyleHint, nsChangeHint)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x50afa01] #02: nsPresContext::SetOverrideDPPX(float)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x5078d77] #03: nsDocumentViewer::InitPresentationStuff(bool)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x507774f] #04: nsDocumentViewer::InitInternal(nsIWidget*, nsISupports*, mozilla::gfx::IntRectTyped<mozilla::gfx::UnknownUnits> const&, bool, bool, bool)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x5077374] #05: nsDocumentViewer::Init(nsIWidget*, mozilla::gfx::IntRectTyped<mozilla::gfx::UnknownUnits> const&)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x50768d6] #06: nsDocShell::SetupNewViewer(nsIContentViewer*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x58e4d4f] #07: nsDocShell::Embed(nsIContentViewer*, char const*, nsISupports*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x58e3bbb] #08: nsDocShell::CreateContentViewer(nsACString_internal const&, nsIRequest*, nsIStreamListener**)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x58b6b00] #09: nsDSURIContentListener::DoContent(nsACString_internal const&, bool, nsIRequest*, nsIStreamListener**, bool*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x58b55c2] #10: nsDocumentOpenInfo::TryContentListener(nsIURIContentListener*, nsIChannel*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x1a3a05e] #11: nsDocumentOpenInfo::DispatchContent(nsIRequest*, nsISupports*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x1a385d4] #12: nsDocumentOpenInfo::OnStartRequest(nsIRequest*, nsISupports*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x1a37e4a] #13: nsBaseChannel::OnStartRequest(nsIRequest*, nsISupports*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x31f165] #14: nsInputStreamPump::OnStateStart()[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x354405] #15: nsInputStreamPump::OnInputStreamReady(nsIAsyncInputStream*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x353f2d] #16: nsInputStreamReadyEvent::Run()[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x190899] #17: nsThread::ProcessNextEvent(bool, bool*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x1c5499] #18: NS_ProcessPendingEvents(nsIThread*, unsigned int)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x2509ec] #19: nsBaseAppShell::NativeEventCallback()[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x4b03e7e] #20: nsAppShell::ProcessGeckoEvents(void*)[/files/mozilla/repos/qq/obj-x86_64-apple-darwin15.6.0/dist/NightlyDebug.app/Contents/MacOS/XUL +0x4b9b642] #21: __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__[/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation +0xaa881]

Comment on attachment 8786953 [details] [diff] [review] Tweak stylo path for nsPresContext::HasCachedStyleData to avoid triggering operations too early during bootstrapping. v1 Review of attachment 8786953 [details] [diff] [review]: ----------------------------------------------------------------- ::: layout/base/nsPresContext.cpp @@ +2503,5 @@ > if (!styleSet) { > // XXXheycam ServoStyleSets do not use the rule tree, so just assume for now > + // that we need to restyle when e.g. dppx changes assuming we're sufficiently > + // bootstrapped. > + return mShell && mShell->DidInitialize(); You don't need the null-check, it's checked above. r=me without it.

Pushed by bholley@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/659772c16de7 Tweak stylo path for nsPresContext::HasCachedStyleData to avoid triggering operations too early during bootstrapping. r=emilio