Comment 16 for bug 184547

FWIW, in a debug build, it displays these lines:
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043
###!!! ASSERTION: Unmatched begin/end?: '!mOldRuleTree', file nsStyleSet.cpp, line 107
WARNING: Unable to test style tree integrity -- no content node: file nsCSSFrameConstructor.cpp, line 10043

The stacktrace with a non-optimized debug build looks like:
#0 0x00007fe163f420e7 in nsRuleNode::WalkRuleTree (this=0x4193a50, aSID=eStyleStruct_Background, aContext=0x41acec8, aRuleData=0x7fff7a5dd390, aSpecificData=0x7fff7a5dd2f0) at nsRuleNode.cpp:1388
#1 0x00007fe163f44810 in nsRuleNode::GetBackgroundData (this=0x4193a50, aContext=0x41acec8) at nsRuleNode.cpp:1211
#2 0x00007fe163f4490b in nsRuleNode::GetStyleBackground (this=0x4193a50, aContext=0x41acec8, aComputeData=1) at nsStyleStructList.h:79
#3 0x00007fe163f4bb5c in nsStyleContext::GetStyleBackground (this=0x41acec8) at nsStyleStructList.h:79
#4 0x00007fe163f4eed3 in nsStyleContext::CalcStyleDifference (this=0x3b07018, aOther=0x41acec8) at nsStyleContext.cpp:472
#5 0x00007fe163da6dcd in CaptureChange (aOldContext=0x3b07018, aNewContext=0x41acec8, aFrame=0x3b070d8, aContent=0x3a49cc0, aChangeList=0x7fff7a5e11e0, aMinChange=7, aChangeToAssume=0)
    at nsFrameManager.cpp:1058
#6 0x00007fe163da739f in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3b070d8, aParentContent=0x3a49c20, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1196
#7 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3b06f00, aParentContent=0x3a499f0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#8 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aba088, aParentContent=0x3a49a90, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#9 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aab338, aParentContent=0x3a49a90, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#10 0x00007fe163da6fdc in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aab2b8, aParentContent=0x3a499a0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1125
#11 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aab048, aParentContent=0x3a499a0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#12 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aaaf30, aParentContent=0x3a37d40, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#13 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3ab9938, aParentContent=0x3a37c60, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#14 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3ab96a8, aParentContent=0x3a37c00, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#15 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3ab95a8, aParentContent=0x3a37c00, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#16 0x00007fe163da6fdc in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3ab9528, aParentContent=0x3a37ae0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1125
#17 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3b308c8, aParentContent=0x3a37a90, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#18 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aee140, aParentContent=0x3a37a90, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#19 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aee028, aParentContent=0x3a379a0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#20 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aede40, aParentContent=0x2694700, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#21 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3aed368, aParentContent=0x26944b0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#22 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3a2c6b0, aParentContent=0x26944b0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#23 0x00007fe163da6fdc in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3a2c630, aParentContent=0x3a2e9a0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1125
#24 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3a2ba78, aParentContent=0x3a0bb30, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#25 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3a2b870, aParentContent=0x26bd580, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#26 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x3a294f8, aParentContent=0x26bd580, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#27 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x38b35a8, aParentContent=0x26bd580, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#28 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x38b37e8, aParentContent=0x0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#29 0x00007fe163da7dd3 in nsFrameManager::ReResolveStyleContext (this=0x268e3a8, aPresContext=0x26b0240, aFrame=0x38b34a0, aParentContent=0x0, aChangeList=0x7fff7a5e11e0, aMinChange=7)
    at nsFrameManager.cpp:1404
#30 0x00007fe163da802b in nsFrameManager::ComputeStyleChangeFor (this=0x268e3a8, aFrame=0x38b34a0, aChangeList=0x7fff7a5e11e0, aMinChange=7) at nsFrameManager.cpp:1470
#31 0x00007fe163d6b912 in nsCSSFrameConstructor::RebuildAllStyleData (this=0x268ea70, aExtraHint=7) at nsCSSFrameConstructor.cpp:13422
#32 0x00007fe163db7a46 in nsPresContext::RebuildAllStyleData (this=0x26b0240, aExtraHint=7) at nsPresContext.cpp:1409
#33 0x00007fe163da5442 in nsPresContext::SetTextZoom (this=0x26b0240, aZoom=1.18920708) at nsPresContext.h:475
#34 0x00007fe163d989d1 in DocumentViewerImpl::SetTextZoom (this=0x2a30520, aTextZoom=1.18920708) at nsDocumentViewer.cpp:2674
#35 0x0000000000485755 in EphyBrowser::SetZoom ()

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