The render tree construction is going horribly wrong (nested columns and dynamic spans) in this test case.
Created attachment 230517 [details]
Attachment 230517 [details] did not pass style-queue:
ERROR: Source/WebCore/rendering/RenderMultiColumnFlowThread.cpp:39: RenderMultiColumnFlowThread::g_shiftingSpanner is incorrectly named. Don't use underscores in your identifier names. [readability/naming/underscores] 
ERROR: Source/WebCore/rendering/RenderMultiColumnFlowThread.cpp:304: Weird number of spaces at line-start. Are you using a 4-space indent? [whitespace/indent] 
ERROR: Source/WebCore/rendering/RenderMultiColumnFlowThread.h:153: g_shiftingSpanner is incorrectly named. Don't use underscores in your identifier names. [readability/naming/underscores] 
Total errors found: 3 in 7 files
If any of these errors are false positives, please file a bug against check-webkit-style.
Fixed in r168043.