fast/text/large-text-composed-char-dos.html sometimes fails on Windows. See the URL for one example. This started happening within the last week. Perhaps r80526 is related?
Almost certainly related. Not sure what exactly is going on though.
It failed on SnowLeopard, too! http://build.webkit.org/results/SnowLeopard%20Intel%20Release%20(Tests)/r80842%20(26633)/fast/text/large-text-composed-char-dos-pretty-diff.html
I disabled the test in r80849.
<rdar://problem/9121050>
fwiw, looking at our dashboard, things changed with r80526. http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20-%20chromium.org&tests=fast%2Ftext%2Flarge-text-composed-char-dos.html
I see what's going on. When a text node length limit cannot be satisfied due to a composed sequence that's longer than 64K, the result depends on what size data chucks are coming in.
Created attachment 85704 [details] composed sequence in adjacent nodes I think that it's ultimately a text rendering bug that composed sequences cannot span text nodes. See attached test case for one manifestation of it.