###!!! ASSERTION: Shouldn't have unconstrained stuff here Thanks to the rules of reflow: 'aReflowState.ComputedWidth() != NS_UNCONSTRAINEDSIZE', file /builds/slave/mozilla-central-macosx-debug/build/layout/generic/nsLeafFrame.cpp, line 107 And it draws "backwards", as if it had a negative width.

Still reproduces on trunk, along with some other asserts/warnings: ASSERTION: non-root reflow roots must not have scrollable overflow: 'target == rootFrame || desiredSize.ScrollableOverflow().IsEqualEdges(boundsRelativeToTarget)', file /builds/slave/m-cen-l64-d-000000000000000000/build/src/layout/base/nsPresShell.cpp, line 9073 WARNING: Scrolled rect smaller than scrollport?: file /builds/slave/m-cen-l64-d-000000000000000000/build/src/layout/generic/nsGfxScrollFrame.cpp, line 5240 [GFX2-]: Ignoring DrawTargetCairo::FillRect() call with out-of-bounds Rect