1396056 - Missing Font Instances in Webrender (MacOS)

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P1)

Description

[Aria Beingessner [:Gankra]]

I am very frequently hitting this assertion

thread 'RenderBackend' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:335
stack backtrace:
   0:        0x105e571b3 - std::sys::imp::backtrace::tracing::imp::unwind_backtrace::h884a721e113c3303
   1:        0x105e63673 - std::panicking::default_hook::{{closure}}::h7a7d734b2824d103
   2:        0x105e632bc - std::panicking::default_hook::h3eb11bd6cbfdc331
   3:        0x105e657e7 - std::panicking::rust_panic_with_hook::h8b9b25777425677b
   4:        0x105e65684 - std::panicking::begin_panic::h69fe06a9d67b6165
   5:        0x105e655f2 - std::panicking::begin_panic_fmt::haf8695bfb6c52436
   6:        0x105e65557 - rust_begin_unwind
   7:        0x105e78740 - core::panicking::panic_fmt::hfedd6515bcee8bb1
   8:        0x105e78644 - core::panicking::panic::hd25e89dc434847c1
   9:        0x105d7ad26 - webrender::frame::Frame::flatten_item::h0dd21a03b813f292
  10:        0x105d81db9 - webrender::frame::Frame::flatten_root::h6a59eb339271e48b
  11:        0x105d81999 - webrender::frame::Frame::flatten_item::h0dd21a03b813f292
  12:        0x105d81db9 - webrender::frame::Frame::flatten_root::h6a59eb339271e48b
  13:        0x105d9dfac - webrender::render_backend::Document::build_scene::h25545439d461eb3c
  14:        0x105da0a72 - webrender::render_backend::RenderBackend::process_document::h4d15f89da71ac125
  15:        0x105da7e63 - webrender::render_backend::RenderBackend::run::h1e46bd6ec338e777
  16:        0x105d4275c - std::sys_common::backtrace::__rust_begin_short_backtrace::h76c48d6378241076
  17:        0x105d4487d - std::panicking::try::do_call::h6f4ae3888def205f


lldb:

frame #12: 0x0000000105d7ad1b XUL`webrender::frame::{{impl}}::flatten_item(self=0x00000001230a3348, item=<unavailable>, pipeline_id=<unavailable>, context=0x00007000061067a8, reference_frame_relative_offset=<unavailable>) at frame.rs:570 [opt]
   567 	                                              info.image_rendering);
   568 	            }
   569 	            SpecificDisplayItem::Text(ref text_info) => {
-> 570 	                let instance = context.resource_cache.get_font_instance(text_info.font_key).unwrap();
   571 	                context.builder.add_text(clip_and_scroll,
   572 	                                         reference_frame_relative_offset,
   573 	                                         item_rect_with_offset,


In particular I get this 100% reliably while starting up the current tip with webrendest + layers-free. Inability to reproduce with nightly suggests my local build has something funky in a cache somewhere? 

I've also seen it a few times while opening tabs, but at the time I thought it was crashing due to the patches I was working on.

Comment 1

[Lee Salzman [:lsalzman]]

That would imply it is using a font that it failed to actually send over first, which should almost never happen. Do you have a test case that can reliably reproduce the issue?

Comment 2

[Aria Beingessner [:Gankra]]

I don't have a simple/clean reproduction. I just: 

build tip 

visit a bunch of websites including:

* https://gankro.github.io/blah/webtests/text.html
* https://arstechnica.com
* https://edgewebfonts.adobe.com/fonts

close the browser

./mach run

crash

Comment 3

[Aria Beingessner [:Gankra]]

Attachment: crashlog.txt

Crash log actually looks a bit interesting (attached). Notably, thread 0:

Thread 0:: Dispatch queue: com.apple.main-thread
0   com.apple.CoreFoundation      	0x00007fffb46aa2a2 CFStringFindWithOptionsAndLocale + 306
1   com.apple.CoreFoundation      	0x00007fffb46aa162 CFStringHasPrefix + 194
2   libFontRegistry.dylib         	0x00007fffb31fda73 TFontEntity::CompareFamilyNames(void const*, void const*, void*) + 127
3   com.apple.CoreFoundation      	0x00007fffb4712e48 __CFSimpleMergeSort + 360
4   com.apple.CoreFoundation      	0x00007fffb4712ddf __CFSimpleMergeSort + 255
5   com.apple.CoreFoundation      	0x00007fffb4712c94 CFSortIndexes + 916
6   com.apple.CoreFoundation      	0x00007fffb4712703 CFQSortArray + 451
7   com.apple.CoreFoundation      	0x00007fffb47124ac CFArraySortValues + 1068
8   libFontRegistry.dylib         	0x00007fffb31fd864 TCFSet<void const*>::CreateSortedArray(long (*)(void const*, void const*, void*), void*, CFArrayCallBacks const*) const + 208
9   libFontRegistry.dylib         	0x00007fffb32259bb XTCopyAvailableFamilyNames2 + 257
10  com.apple.CoreText            	0x00007fffb5cd9a84 TDescriptorSource::CopyAvailableFamilyNames(__CFString const*) const + 132
11  com.apple.CoreText            	0x00007fffb5cd9996 CTFontManagerCopyAvailableFontFamilyNames + 35
12  XUL                           	0x000000010f99a198 gfxMacPlatformFontList::InitFontListForPlatform() + 744 (gfxMacPlatformFontList.mm:868)
13  XUL                           	0x000000010f978afc gfxPlatformFontList::InitFontList() + 444 (gfxPlatformFontList.cpp:291)
14  XUL                           	0x000000010f979631 gfxPlatformFontList::UpdateFontList() + 17 (nsTHashtable.h:250)
15  XUL                           	0x000000010f999727 gfxMacPlatformFontList::RegisteredFontsChangedNotificationCallback(__CFNotificationCenter*, void*, __CFString const*, void const*, __CFDictionary const*) + 39 (gfxMacPlatformFontList.mm:1084)
16  com.apple.CoreFoundation      	0x00007fffb473745c __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12
17  com.apple.CoreFoundation      	0x00007fffb473735b _CFXRegistrationPost + 427
18  com.apple.CoreFoundation      	0x00007fffb47370c2 ___CFXNotificationPost_block_invoke + 50
19  com.apple.CoreFoundation      	0x00007fffb46f4523 -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1827
20  com.apple.CoreFoundation      	0x00007fffb46f355c _CFXNotificationPost + 604
21  com.apple.CoreFoundation      	0x00007fffb473cbd5 CFNotificationCenterPostNotification + 117
22  libFontRegistry.dylib         	0x00007fffb3201c57 AsynchronousLocalNotificationTimerCallBack(__CFRunLoopTimer*, void*) + 18
23  com.apple.CoreFoundation      	0x00007fffb472ac54 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
24  com.apple.CoreFoundation      	0x00007fffb472a8df __CFRunLoopDoTimer + 1071
25  com.apple.CoreFoundation      	0x00007fffb472a43a __CFRunLoopDoTimers + 298
26  com.apple.CoreFoundation      	0x00007fffb4721b81 __CFRunLoopRun + 2065
27  com.apple.CoreFoundation      	0x00007fffb4721114 CFRunLoopRunSpecific + 420
28  com.apple.HIToolbox           	0x00007fffb3c81ebc RunCurrentEventLoopInMode + 240
29  com.apple.HIToolbox           	0x00007fffb3c81bf9 ReceiveNextEventCommon + 184
30  com.apple.HIToolbox           	0x00007fffb3c81b26 _BlockUntilNextEventMatchingListInModeWithFilter + 71
31  com.apple.AppKit              	0x00007fffb221aa54 _DPSNextEvent + 1120
32  com.apple.AppKit              	0x00007fffb29967ee -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 2796
33  XUL                           	0x0000000110c3b6b6 -[GeckoNSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 86 (nsAppShell.mm:158)
34  com.apple.AppKit              	0x00007fffb220f3db -[NSApplication run] + 926
35  XUL                           	0x0000000110c3c58a nsAppShell::Run() + 250 (nsAppShell.mm:715)
36  XUL                           	0x0000000111f7ad74 nsAppStartup::Run() + 68 (nsAppStartup.cpp:288)
37  XUL                           	0x00000001120093ab XREMain::XRE_mainRun() + 3371 (nsAppRunner.cpp:4653)
38  XUL                           	0x0000000112009c1f XREMain::XRE_main(int, char**, mozilla::BootstrapConfig const&) + 1071 (nsAppRunner.cpp:4810)
39  XUL                           	0x000000011200a1af XRE_main(int, char**, mozilla::BootstrapConfig const&) + 239 (nsAppRunner.cpp:4905)
40  org.mozilla.nightly           	0x000000010e67f167 main + 567 (nsBrowserApp.cpp:236)
41  libdyld.dylib                 	0x00007fffc9ea1235 start + 1

Comment 4

[Aria Beingessner [:Gankra]]

I added some event logging, as it seemed we were often crashing concurrently with font update notifications.

It appears something installs a bunch of Noto fonts on startup, which repeatedly clobbers the font whole font cache, which races with us rendering the first frame.

MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5280 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansCarian-Regular.ttf#postscript-name=NotoSansCarian"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b53c0 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansCham-Regular.ttf#postscript-name=NotoSansCham"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5400 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansCoptic-Regular.ttf#postscript-name=NotoSansCoptic"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5440 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansCuneiform-Regular.ttf#postscript-name=NotoSansCuneiform"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5480 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansCypriot-Regular.ttf#postscript-name=NotoSansCypriot"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5500 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansEgyptianHieroglyphs-Regular.ttf#postscript-name=NotoSansEgyptianHieroglyphs"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b54c0 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansGlagolitic-Regular.ttf#postscript-name=NotoSansGlagolitic"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5540 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansGothic-Regular.ttf#postscript-name=NotoSansGothic"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5580 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansHanunoo-Regular.ttf#postscript-name=NotoSansHanunoo"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5600 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansImperialAramaic-Regular.ttf#postscript-name=NotoSansImperialAramaic"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5640 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansInscriptionalPahlavi-Regular.ttf#postscript-name=NotoSansInscriptionalPahlavi"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5680 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansInscriptionalParthian-Regular.ttf#postscript-name=NotoSansInscriptionalParthian"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b55c0 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansJavanese-Regular.ttf#postscript-name=NotoSansJavanese"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5700 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansKaithi-Regular.ttf#postscript-name=NotoSansKaithi"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5780 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansKayahLi-Regular.ttf#postscript-name=NotoSansKayahLi"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5800 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansKharoshthi-Regular.ttf#postscript-name=NotoSansKharoshthi"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5880 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansLepcha-Regular.ttf#postscript-name=NotoSansLepcha"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5900 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansLimbu-Regular.ttf#postscript-name=NotoSansLimbu"
)
}
RemoveExpiredFontKeys Deleting ScaledFont: 27
RemoveExpiredFontKeys Deleting ScaledFont: 64
RemoveExpiredFontKeys Deleting ScaledFont: 5
RemoveExpiredFontKeys Deleting ScaledFont: 67
RemoveExpiredFontKeys Deleting ScaledFont: 62
RemoveExpiredFontKeys Deleting UnscaledFont: 61
RemoveExpiredFontKeys Deleting UnscaledFont: 63
RemoveExpiredFontKeys Deleting UnscaledFont: 66
RemoveExpiredFontKeys Deleting UnscaledFont: 4
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5940 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansLinearB-Regular.ttf#postscript-name=NotoSansLinearB"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5980 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansLisu-Regular.ttf#postscript-name=NotoSansLisu"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5a00 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansLycian-Regular.ttf#postscript-name=NotoSansLycian"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5a40 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansLydian-Regular.ttf#postscript-name=NotoSansLydian"
)
}
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5a80 [0x7fffcf745thread 'daRenderBackend0' panicked at ']Missing font! FontInstanceKey(IdNamespace(3), 5)', >/Users/ABeingessner/dev/gecko/gfx/webrender/src/frame.rs{:t573y
pe = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansMandaic-Regular.ttf#postscript-name=NotoSansMandaic"
)
}
stack backtrace:
   0:        0x1117327a3 - std::sys::imp::backtrace::tracing::imp::unwind_backtrace::h884a721e113c3303
MacOS FontsChangedNotification:    1:        0x11173ec63 - std::panicking::<default_hookC::FB{a{sclosurei}c}H::ah7a7d734b2824d103s
h 0x11c9b5b40 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansMeeteiMayek-Regular.ttf#postscript-name=NotoSansMeeteiMayek"
)
}
   2:        0x11173e8ac - std::panicking::default_hook::h3eb11bd6cbfdc331
   3:        0x111740dd7 - std::panicking::rust_panic_with_hook::h8b9b25777425677b
   4:        0x111740c74 - std::panicking::begin_panic::h69fe06a9d67b6165
   5:        0x111740be2 - std::panicking::begin_panic_fmt::haf8695bfb6c52436
   6:        0x111624f96 - webrender::frame::Frame::flatten_item::h0dd21a03b813f292
   7:        0x11162c019 - webrender::frame::Frame::flatten_root::h6a59eb339271e48b
MacOS FontsChangedNotification: <CFBasicHash 0x11c9b5b00 [0x7fffcf745da0]>{type = immutable dict, count = 1,
entries =>
    2 : <CFString 0x7fffcf1f2540 [0x7fffcf745da0]>{contents = "CTFontManagerAvailableFontURLsAdded"} = (
    "file:///Library/Application%20Support/Apple/Fonts/Language%20Support/NotoSansMongolian-Regular.ttf#postscript-name=NotoSansMongolian"
)
}
   8:        0x11162bbf8 - webrender::frame::Frame::flatten_item::h0dd21a03b813f292
   9:        0x11162c019 - webrender::frame::Frame::flatten_root::h6a59eb339271e48b
  10:        0x11164820c - webrender::render_backend::Document::build_scene::h25545439d461eb3c
  11:        0x11164c8e3 - webrender::render_backend::RenderBackend::process_document::h4d15f89da71ac125
  12:        0x1116520c3 - webrender::render_backend::RenderBackend::run::h1e46bd6ec338e777
  13:        0x1115ec96c - std::sys_common::backtrace::__rust_begin_short_backtrace::h76c48d6378241076
  14:        0x1115eea8d - std::panicking::try::do_call::h6f4ae3888def205f
Redirecting call to abort() to mozalloc_abort

Comment 5

[Lee Salzman [:lsalzman]]

Upstream WebRender fix: https://github.com/servo/webrender/pull/1664

Comment 6

[Jonathan Kew [:jfkthame]]

Ouch. This is a result of the patch in bug 1392659, which activates a bunch of fonts shipped for "Language Support" on macOS. We may be able to optimize this so that they're all activated in a single batch, though, which I'd assume will be much more efficient. I'll look into that...

Comment 7

[Markus Stange [:mstange]]

https://github.com/servo/webrender/pull/1664 was picked up in 1397831, so the crash is fixed. I'm resolving this bug.

Jonathan, do you want to file a new bug for the optimization idea from comment 6?

Comment 8

[Jonathan Kew [:jfkthame]]

(In reply to Markus Stange [:mstange] from comment #7)
> https://github.com/servo/webrender/pull/1664 was picked up in 1397831, so
> the crash is fixed. I'm resolving this bug.
> 
> Jonathan, do you want to file a new bug for the optimization idea from
> comment 6?

That was done in bug 1397292.