Created attachment 266716 [details] testcase See the attached testcase. The large operator (black square) has height 0 and so the scripts (red and green bars) are badly placed. I think it's a regression, as it used to work when I implemented largeop support.
Created attachment 266717 [details] Screenshot of the testcase in gecko
Created attachment 266718 [details] Screenshot in current webkit nightly & release
Created attachment 266719 [details] Patch adding a test for this bug
Created attachment 266984 [details] Patch
Committed r193829: <http://trac.webkit.org/changeset/193829>