Bug 1421887 - fix the row index to get the right cell. r=dbaron

MozReview-Commit-ID: 4wIdFxeETiW

layout/tables/nsCellMap.cpp

@@ -898,9 +898,12 @@ bool nsTableCellMap::RowHasSpanningCells(int32_t aRowIndex,
   return false;
 }
 
+// FIXME: The only value callers pass for aSide is eLogicalSideBEnd.
+// Consider removing support for the other three values.
 void
 nsTableCellMap::ResetBStartStart(LogicalSide aSide,
                                  nsCellMap&  aCellMap,
+                                 uint32_t    aRowGroupStart,
                                  uint32_t    aRowIndex,
                                  uint32_t    aColIndex,
                                  bool        aIsBEndIEnd)
@@ -915,7 +918,7 @@ nsTableCellMap::ResetBStartStart(LogicalSide aSide,
     aRowIndex++;
     MOZ_FALLTHROUGH;
   case eLogicalSideBStart:
-    cellData = (BCCellData*)aCellMap.GetDataAt(aRowIndex, aColIndex);
+    cellData = (BCCellData*)aCellMap.GetDataAt(aRowIndex - aRowGroupStart, aColIndex);
     if (cellData) {
       bcData = &cellData->mData;
     }
@@ -938,7 +941,7 @@ nsTableCellMap::ResetBStartStart(LogicalSide aSide,
     aColIndex++;
     MOZ_FALLTHROUGH;
   case eLogicalSideIStart:
-    cellData = (BCCellData*)aCellMap.GetDataAt(aRowIndex, aColIndex);
+    cellData = (BCCellData*)aCellMap.GetDataAt(aRowIndex - aRowGroupStart, aColIndex);
     if (cellData) {
       bcData = &cellData->mData;
     }

layout/tables/nsCellMap.h

@@ -191,6 +191,7 @@ protected:
 public:
   void ResetBStartStart(mozilla::LogicalSide aSide,
                         nsCellMap& aCellMap,
+                        uint32_t   aRowGroupStart,
                         uint32_t   aYPos,
                         uint32_t   aXPos,
                         bool       aIsBEndIEnd = false);

layout/tables/nsTableFrame.cpp

@@ -6473,6 +6473,7 @@ nsTableFrame::CalcBCBorders()
           // new segment
           if (iter.mCellMap) {
             tableCellMap->ResetBStartStart(eLogicalSideBEnd, *iter.mCellMap,
+                                           iter.mRowGroupStart,
                                            info.GetCellEndRowIndex(),
                                            info.GetCellEndColIndex() + 1);
           }