Filed by: malexandru [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=258398128&repo=mozilla-central
Full log: https://queue.taskcluster.net/v1/task/aRnE_voDRxi06yVZFzQCfQ/runs/0/artifacts/public/logs/live_backing.log

[task 2019-07-25T22:58:26.060Z] 22:58:26 INFO - zombiecheck | Checking for orphan process with PID: 1712
[task 2019-07-25T22:58:26.069Z] 22:58:26 INFO - mozcrash Downloading symbols from: https://queue.taskcluster.net/v1/task/fbHjRCazQjCFCbs1sqeOKQ/artifacts/public/build/target.crashreporter-symbols.zip
[task 2019-07-25T22:58:28.994Z] 22:58:28 INFO - mozcrash Copy/paste: /Users/cltbld/tasks/task_1564095133/build/macosx64-minidump_stackwalk /var/folders/4z/gmjb5mfn7m15rdy406rr641h000017/T/tmpC9ZU2I.mozrunner/minidumps/15BFD995-6CA3-4C4E-95D6-DB11397CD1E5.dmp /var/folders/4z/gmjb5mfn7m15rdy406rr641h000017/T/tmp1IDRE9
[task 2019-07-25T22:58:34.391Z] 22:58:34 INFO - mozcrash Saved minidump as /Users/cltbld/tasks/task_1564095133/build/blobber_upload_dir/15BFD995-6CA3-4C4E-95D6-DB11397CD1E5.dmp
[task 2019-07-25T22:58:34.391Z] 22:58:34 INFO - mozcrash Saved app info as /Users/cltbld/tasks/task_1564095133/build/blobber_upload_dir/15BFD995-6CA3-4C4E-95D6-DB11397CD1E5.extra
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - PROCESS-CRASH | devtools/client/inspector/test/browser_inspector_breadcrumbs_mutations.js | application crashed [@ js::GCMarker::processMarkStackTop(js::SliceBudget&)]
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - Crash dump filename: /var/folders/4z/gmjb5mfn7m15rdy406rr641h000017/T/tmpC9ZU2I.mozrunner/minidumps/15BFD995-6CA3-4C4E-95D6-DB11397CD1E5.dmp
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - Operating system: Mac OS X
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - 10.14.5 18F132
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - CPU: amd64
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - family 6 model 69 stepping 1
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - 4 CPUs
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO -
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - GPU: UNKNOWN
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO -
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - Crash reason: EXC_BAD_ACCESS / KERN_INVALID_ADDRESS
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - Crash address: 0xfffffffffa2f6198
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO - Process uptime: 20 seconds
[task 2019-07-25T22:58:34.528Z] 22:58:34 INFO -
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - Thread 0 (crashed)
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - 0 XUL!js::GCMarker::processMarkStackTop(js::SliceBudget&) [Marking.cpp:92748f5caf89eead6ae37e57d822359f256a08cf : 1846 + 0x0]
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - rax = 0x000000010a2f6190 rdx = 0x0000000000000000
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - rcx = 0x00000000be000001 rbx = 0x0000000000000000
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - rsi = 0x000024c5f2e0eec0 rdi = 0x0000000000001dd9
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - rbp = 0x00007ffeeda0f6f0 rsp = 0x00007ffeeda0f690
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - r8 = 0x0000100000000001 r9 = 0x0844108422084221
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - r10 = 0x000000010321a180 r11 = 0xfffe000000000000
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - r12 = 0x00002b417afc71d8 r13 = 0x000000010321a198
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - r14 = 0x00002b417afdf280 r15 = 0xfffb000000000000
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - rip = 0x000000010994bda9
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - Found by: given as instruction pointer in context
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - 1 XUL!js::GCMarker::markUntilBudgetExhausted(js::SliceBudget&) [Marking.cpp:92748f5caf89eead6ae37e57d822359f256a08cf : 1625 + 0xb]
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - rbp = 0x00007ffeeda0f740 rsp = 0x00007ffeeda0f700
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - rip = 0x0000000109934e5b
[task 2019-07-25T22:58:34.529Z] 22:58:34 INFO - Found by: previous frame's frame pointer
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - 2 XUL!js::gc::GCRuntime::markGrayReferencesInCurrentGroup(js::FreeOp*, js::SliceBudget&) [GC.cpp:92748f5caf89eead6ae37e57d822359f256a08cf : 5577 + 0x29]
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - rbp = 0x00007ffeeda0f7b0 rsp = 0x00007ffeeda0f750
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - rip = 0x000000010992f035
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - Found by: previous frame's frame pointer
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - 3 XUL!sweepaction::SweepActionSequence::run(js::gc::SweepAction::Args&) [GC.cpp:92748f5caf89eead6ae37e57d822359f256a08cf : 6581 + 0x9]
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - rbp = 0x00007ffeeda0f7e0 rsp = 0x00007ffeeda0f7c0
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - rip = 0x000000010995becc
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - Found by: previous frame's frame pointer
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - 4 XUL!sweepaction::SweepActionForEach<js::gc::SweepGroupsIter, JSRuntime*>::run(js::gc::SweepAction::Args&) [GC.cpp:92748f5caf89eead6ae37e57d822359f256a08cf : 6616 + 0xd]
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - rbp = 0x00007ffeeda0f850 rsp = 0x00007ffeeda0f7f0
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - rip = 0x0000000109956b4d
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - Found by: previous frame's frame pointer
[task 2019-07-25T22:58:34.530Z] 22:58:34 INFO - 5 XUL!js::gc::GCRuntime::incrementalSlice(js::SliceBudget&, mozilla::Maybe<JSGCInvocationKind> const&, JS::GCReason, js::gc::AutoGCSession&) [GC.cpp:92748f5caf89eead6ae37e57d822359f256a08cf : 7282 + 0x14d]

Filed 1 week ago, and only 1 failure occurred since then. Marking as a P3 for now.