==1844== 
==1844== Invalid read of size 1
==1844==    at 0x82927E2: nsBlockFrame::ReflowDirtyLines(nsBlockReflowState&, int) (nsBlockFrame.cpp:2206)
==1844==    by 0x8295377: nsBlockFrame::Reflow(nsPresContext*, nsHTMLReflowMetrics&, nsHTMLReflowState const&, unsigned&) (nsBlockFrame.cpp:904)
==1844==    by 0x829B31D: nsContainerFrame::ReflowChild(nsIFrame*, nsPresContext*, nsHTMLReflowMetrics&, nsHTMLReflowState const&, int, int, unsigned, unsigned&) (nsContainerFrame.cpp:909)
==1844==    by 0x82AD49A: CanvasFrame::Reflow(nsPresContext*, nsHTMLReflowMetrics&, nsHTMLReflowState const&, unsigned&) (nsHTMLFrame.cpp:531)
==1844==    by 0x829B31D: nsContainerFrame::ReflowChild(nsIFrame*, nsPresContext*, nsHTMLReflowMetrics&, nsHTMLReflowState const&, int, int, unsigned, unsigned&) (nsContainerFrame.cpp:909)
==1844==    by 0x82AA66C: nsHTMLScrollFrame::ReflowScrolledFrame(ScrollReflowState const&, int, int, nsHTMLReflowMetrics*, int) (nsGfxScrollFrame.cpp:515)
==1844==    by 0x82AA9B3: nsHTMLScrollFrame::ReflowContents(ScrollReflowState*, nsHTMLReflowMetrics const&) (nsGfxScrollFrame.cpp:570)
==1844==    by 0x82AB32F: nsHTMLScrollFrame::Reflow(nsPresContext*, nsHTMLReflowMetrics&, nsHTMLReflowState const&, unsigned&) (nsGfxScrollFrame.cpp:768)
==1844==    by 0x829B31D: nsContainerFrame::ReflowChild(nsIFrame*, nsPresContext*, nsHTMLReflowMetrics&, nsHTMLReflowState const&, int, int, unsigned, unsigned&) (nsContainerFrame.cpp:909)
==1844==    by 0x82DAFAC: ViewportFrame::Reflow(nsPresContext*, nsHTMLReflowMetrics&, nsHTMLReflowState const&, unsigned&) (nsViewportFrame.cpp:239)
==1844==    by 0x8285DDC: PresShell::ResizeReflow(int, int) (nsPresShell.cpp:3104)
==1844==    by 0x84234F3: nsViewManager::DoSetWindowDimensions(int, int) (nsViewManager.h:418)
==1844==  Address 0x27 is not stack'd, malloc'd or (recently) free'd