Bot says that this started in this range <http://trac.webkit.org/log/?verbose=on&rev=163079&stop_rev=163074>, which probably implicates <http://trac.webkit.org/changeset/163079>. Note that this test was crashing about a week ago as well, but that was for an entirely different reason. Sample crash: <http://build.webkit.org/results/Apple%20MountainLion%20Debug%20WK2%20(Tests)/r163080%20(15681)/fast/events/page-visibility-iframe-move-test-crash-log.txt> Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 com.apple.JavaScriptCore 0x000000010d81b75a WTFCrash + 42 (Assertions.cpp:333) 1 com.apple.WebCore 0x00000001101d647b WebCore::RenderView::paint(WebCore::PaintInfo&, WebCore::LayoutPoint const&) + 91 (RenderView.cpp:479) 2 com.apple.WebCore 0x0000000110032924 WebCore::RenderLayer::paintBackgroundForFragments(WTF::Vector<WebCore::LayerFragment, 1ul, WTF::CrashOnOverflow> const&, WebCore::GraphicsContext*, WebCore::GraphicsContext*, WebCore::LayoutRect const&, bool, WebCore::RenderLayer::LayerPaintingInfo const&, unsigned int, WebCore::RenderObject*) + 708 (RenderLayer.cpp:4302) 3 com.apple.WebCore 0x000000011002fcc3 WebCore::RenderLayer::paintLayerContents(WebCore::GraphicsContext*, WebCore::RenderLayer::LayerPaintingInfo const&, unsigned int) + 1875 (RenderLayer.cpp:4051) 4 com.apple.WebCore 0x000000011005dcd7 WebCore::RenderLayerBacking::paintIntoLayer(WebCore::GraphicsLayer const*, WebCore::GraphicsContext*, WebCore::IntRect const&, unsigned int, unsigned int) + 551 (RenderLayerBacking.cpp:2203) 5 com.apple.WebCore 0x000000011005e000 WebCore::RenderLayerBacking::paintContents(WebCore::GraphicsLayer const*, WebCore::GraphicsContext&, unsigned int, WebCore::IntRect const&) + 608 (RenderLayerBacking.cpp:2248)
Hmm, two iterations in a row crashed, but the third one didn't, so it's possible that another recent change made the test flaky.
So, it only happened twice, and is green since. Can't blame this revision I guess.
Thanks for the heads up! I'm taking a look anyway, maybe I spot something fishy.