Changes

* should table special height reflows mark dirty or ensure nsHTMLReflowState::mFlags.mVResize is set and depend on vertical resize optimizations?

* We can end up in a state where <code>mDirtyRoots</code> is empty after a <code>FrameNeedsReflow()</code> call -- when <code>nsGfxScrollFrameInner::LayoutScrollbars</code> sets attributes on the slider we end up in <code>nsSliderFrame::AttributeChanged</code> which calls FrameNeedsReflow(). Should we be checking that boolean that the scrollframe uses to tell itself that it's not a real curpos change?

== Future Testing Tasks ==