Bug 1720618 - Remove redundant checks from nsTableFrame::ExpandBCDamageArea. r=dholbert

Differential Revision: https://phabricator.services.mozilla.com/D119935

layout/tables/nsTableFrame.cpp

@@ -4934,8 +4934,8 @@ void nsTableFrame::ExpandBCDamageArea(TableArea& aArea) const {
         }
       }
       // check for spanners on the left and right
-      int32_t iterStartY = -1;
-      int32_t iterEndY = -1;
+      int32_t iterStartY;
+      int32_t iterEndY;
       if ((dStartY >= rgStartY) && (dStartY <= rgEndY)) {
         // the damage area starts in the row group
         iterStartY = dStartY;
@@ -4948,8 +4948,12 @@ void nsTableFrame::ExpandBCDamageArea(TableArea& aArea) const {
         // the damage area contains the row group
         iterStartY = rgStartY;
         iterEndY = rgEndY;
+      } else {
+        // the damage area does not overlap the row group
+        continue;
       }
-      if ((iterStartY >= 0) && (iterEndY >= 0)) {
+      NS_ASSERTION(iterStartY >= 0 && iterEndY >= 0,
+                   "table index values are expected to be nonnegative");
       for (int32_t y = iterStartY; y <= iterEndY; y++) {
         if (uint32_t(y - rgStartY) >= cellMap->mRows.Length()) ABORT0();
         const nsCellMap::CellDataArray& row = cellMap->mRows[y - rgStartY];
@@ -4968,7 +4972,6 @@ void nsTableFrame::ExpandBCDamageArea(TableArea& aArea) const {
       }
     }
   }
-  }
   if (haveSpanner) {
     // make the damage area the whole table
     aArea.StartCol() = 0;