Found with debug build. /home/worker/workspace/build/src/gfx/skia/skia/src/core/SkBitmapProcState.cpp:553: fatal error: ""iY0 == iY2"" Abort from sk_abort Hit MOZ_CRASH() at /home/worker/workspace/build/src/memory/mozalloc/mozalloc_abort.cpp:33 ASAN:DEADLYSIGNAL ================================================================= ==7677==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x0000004e1f23 bp 0x7fffe2dfba00 sp 0x7fffe2dfb9f0 T0) #0 0x4e1f22 in mozalloc_abort(char const*) /home/worker/workspace/build/src/memory/mozalloc/mozalloc_abort.cpp:33:5 #1 0x7f9206379024 in sk_abort_no_print() /home/worker/workspace/build/src/gfx/skia/skia/src/ports/SkMemory_mozalloc.cpp:16:5 #2 0x7f92060b349e in S32_D32_constX_shaderproc(void const*, int, int, unsigned int*, int) /home/worker/workspace/build/src/gfx/skia/skia/src/core/SkBitmapProcState.cpp:553:13 #3 0x7f92060bc38a in BitmapProcShaderContext::shadeSpan(int, int, unsigned int*, int) /home/worker/workspace/build/src/gfx/skia/skia/src/core/SkBitmapProcShader.cpp:72:13 #4 0x7f9205eb7ce6 in SkARGB32_Shader_Blitter::blitRect(int, int, int, int) /home/worker/workspace/build/src/gfx/skia/skia/src/core/SkBlitter_ARGB32.cpp:452:17 #5 0x7f9205f027df in antifilldot8(int, int, int, int, SkBlitter*, bool) /home/worker/workspace/build/src/gfx/skia/skia/src/core/SkScan_Antihair.cpp:678:17 #6 0x7f9205f00f47 in antifillrect(SkRect const&, SkBlitter*) /home/worker/workspace/build/src/gfx/skia/skia/src/core/SkScan_Antihair.cpp:765:5 ... see log.txt for full log.

This doesn't appear to cause a crash with MOZ_SKIA_DISABLE_ASSERTS=1. It is just a case of the debug code in Skia rounding a bit differently with large numbers depending on paths in the bitmap proc shader. This won't cause any problems in release. I think it is best if we just leave this one as-is and mark as low-priority.