Fix the final two exhaustive lint check cases with nolint tags.

Author: rsned

s2/edge_crosser.go

@@ -149,11 +149,13 @@ func (e *EdgeCrosser) ChainCrossingSign(d Point) Crossing {
 func (e *EdgeCrosser) EdgeOrVertexChainCrossing(d Point) bool {
 	// We need to copy e.c since it is clobbered by ChainCrossingSign.
 	c := e.c
-	switch e.ChainCrossingSign(d) { // nolint exhaustive - the missing case is the final return.
+	switch e.ChainCrossingSign(d) {
 	case DoNotCross:
 		return false
 	case Cross:
 		return true
+	case MaybeCross:
+		// fall through
 	}
 	return VertexCrossing(e.a, e.b, c, d)
 }

s2/shapeindex.go

@@ -1026,7 +1026,7 @@ func (s *ShapeIndex) updateEdges(pcell *PaddedCell, edges []*clippedEdge, t *tra
 		// the existing cell contents by absorbing the cell.
 		iter := s.Iterator()
 		r := iter.LocateCellID(pcell.id)
-		switch r { // nolint exhaustive
+		switch r {
 		case Disjoint:
 			disjointFromIndex = true
 		case Indexed:
@@ -1035,7 +1035,7 @@ func (s *ShapeIndex) updateEdges(pcell *PaddedCell, edges []*clippedEdge, t *tra
 			s.absorbIndexCell(pcell, iter, edges, t)
 			indexCellAbsorbed = true
 			disjointFromIndex = true
-		default:
+		case Subdivided:
 			// TODO(rsned): Figure out the right way to deal with
 			// this case since we don't DCHECK.
 			// ABSL_DCHECK_EQ(SUBDIVIDED, r)