Don't construct cell reflow states with a row group reflow state as their parent; instead, always link in a table row reflow state as appropriate. (Bug 627842, patch 3.875) r=roc

Fixes assertion on layout/reftests/bugs/409084-1a.html once the rest
of the inflation patches land.

layout/tables/nsTableRowGroupFrame.cpp

@@ -951,6 +951,8 @@ nsTableRowGroupFrame::SplitSpanningCells(nsPresContext&           aPresContext,
   aFirstTruncatedRow = nsnull;
   aDesiredHeight     = 0;
 
+  bool borderCollapse =
+    static_cast<nsTableFrame*>(aTable.GetFirstInFlow())->IsBorderCollapse();
   PRInt32 lastRowIndex = aLastRow.GetRowIndex();
   bool wasLast = false;
   // Iterate the rows between aFirstRow and aLastRow
@@ -970,7 +972,21 @@ nsTableRowGroupFrame::SplitSpanningCells(nsPresContext&           aPresContext,
         nscoord cellAvailHeight = aSpanningRowBottom - rowPos.y;
         NS_ASSERTION(cellAvailHeight >= 0, "No space for cell?");
         bool isTopOfPage = (row == &aFirstRow) && aFirstRowIsTopOfPage;
-        nscoord cellHeight = row->ReflowCellFrame(&aPresContext, aReflowState,
+
+        nsRect rowRect = row->GetRect();
+        nsSize rowAvailSize(aReflowState.availableWidth,
+                            NS_MAX(aReflowState.availableHeight - rowRect.y,
+                                   0));
+        // don't let the available height exceed what
+        // CalculateRowHeights set for it
+        rowAvailSize.height = NS_MIN(rowAvailSize.height, rowRect.height);
+        nsHTMLReflowState rowReflowState(&aPresContext, aReflowState,
+                                         row, rowAvailSize,
+                                         -1, -1, false);
+        InitChildReflowState(aPresContext, borderCollapse, rowReflowState);
+        rowReflowState.mFlags.mIsTopOfPage = isTopOfPage; // set top of page
+
+        nscoord cellHeight = row->ReflowCellFrame(&aPresContext, rowReflowState,
                                                   isTopOfPage, cell,
                                                   cellAvailHeight, status);
         aDesiredHeight = NS_MAX(aDesiredHeight, rowPos.y + cellHeight);