According to the spec the ::first-line pseudo-element do not apply to grid containers (neither to flexboxes). This is not working as expected in all the situations, so I'll provide a patch to fix the issues. This has already landed in Blink: https://src.chromium.org/viewvc/blink?view=rev&revision=180043
Created attachment 237786 [details] Patch
Comment on attachment 237786 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=237786&action=review > Source/WebCore/rendering/RenderBlock.cpp:3022 > +static inline bool isRenderBlockFlowOrRenderButton(RenderObject* renderObject) This function should take a RenderElement&, not a RenderObject*.
Created attachment 237801 [details] Patch
Comment on attachment 237801 [details] Patch Rejecting attachment 237801 [details] from commit-queue. Failed to run "['/Volumes/Data/EWS/WebKit/Tools/Scripts/webkit-patch', '--status-host=webkit-queues.appspot.com', '--bot-id=webkit-cq-01', 'validate-changelog', '--check-oops', '--non-interactive', 237801, '--port=mac']" exit_code: 1 cwd: /Volumes/Data/EWS/WebKit ChangeLog entry in LayoutTests/ChangeLog contains OOPS!. Full output: http://webkit-queues.appspot.com/results/5866952681586688
Created attachment 237856 [details] Patch
Comment on attachment 237856 [details] Patch Clearing flags on attachment: 237856 Committed r173444: <http://trac.webkit.org/changeset/173444>
All reviewed patches have been landed. Closing bug.