Simplify.

d3.js

@@ -4699,7 +4699,7 @@ d3 = function() {
     return halfEdges.length;
   };
   function d3_geom_voronoiCloseCells(extent) {
-    var x0 = extent[0][0], x1 = extent[1][0], y0 = extent[0][1], y1 = extent[1][1], x2, y2, x3, y3, cells = d3_geom_voronoiCells, iCell = cells.length, cell, iHalfEdge, halfEdges, nHalfEdges, edge, start, end;
+    var x0 = extent[0][0], x1 = extent[1][0], y0 = extent[0][1], y1 = extent[1][1], x2, y2, x3, y3, cells = d3_geom_voronoiCells, iCell = cells.length, cell, iHalfEdge, halfEdges, nHalfEdges, start, end;
     while (iCell--) {
       cell = cells[iCell];
       if (!cell || !cell.prepare()) continue;
@@ -4710,7 +4710,7 @@ d3 = function() {
         end = halfEdges[iHalfEdge].end(), x3 = end.x, y3 = end.y;
         start = halfEdges[++iHalfEdge % nHalfEdges].start(), x2 = start.x, y2 = start.y;
         if (abs(x3 - x2) > ε || abs(y3 - y2) > ε) {
-          edge = d3_geom_voronoiCreateBorderEdge(cell.site, end, abs(x3 - x0) < ε && y1 - y3 > ε ? {
+          halfEdges.splice(iHalfEdge, 0, new d3_geom_voronoiHalfEdge(d3_geom_voronoiCreateBorderEdge(cell.site, end, abs(x3 - x0) < ε && y1 - y3 > ε ? {
             x: x0,
             y: abs(x2 - x0) < ε ? y2 : y1
           } : abs(y3 - y1) < ε && x1 - x3 > ε ? {
@@ -4722,8 +4722,7 @@ d3 = function() {
           } : abs(y3 - y0) < ε && x3 - x0 > ε ? {
             x: abs(y2 - y0) < ε ? x2 : x0,
             y: y0
-          } : null);
-          halfEdges.splice(iHalfEdge, 0, new d3_geom_voronoiHalfEdge(edge, cell.site, null));
+          } : null), cell.site, null));
           ++nHalfEdges;
         }
       }

src/geom/voronoi/cell.js

@@ -32,7 +32,6 @@ function d3_geom_voronoiCloseCells(extent) {
       iHalfEdge,
       halfEdges,
       nHalfEdges,
-      edge,
       start,
       end;
 
@@ -46,13 +45,12 @@ function d3_geom_voronoiCloseCells(extent) {
       end = halfEdges[iHalfEdge].end(), x3 = end.x, y3 = end.y;
       start = halfEdges[++iHalfEdge % nHalfEdges].start(), x2 = start.x, y2 = start.y;
       if (abs(x3 - x2) > ε || abs(y3 - y2) > ε) {
-        edge = d3_geom_voronoiCreateBorderEdge(cell.site, end,
+        halfEdges.splice(iHalfEdge, 0, new d3_geom_voronoiHalfEdge(d3_geom_voronoiCreateBorderEdge(cell.site, end,
             abs(x3 - x0) < ε && y1 - y3 > ε ? {x: x0, y: abs(x2 - x0) < ε ? y2 : y1}
             : abs(y3 - y1) < ε && x1 - x3 > ε ? {x: abs(y2 - y1) < ε ? x2 : x1, y: y1}
             : abs(x3 - x1) < ε && y3 - y0 > ε ? {x: x1, y: abs(x2 - x1) < ε ? y2 : y0}
             : abs(y3 - y0) < ε && x3 - x0 > ε ? {x: abs(y2 - y0) < ε ? x2 : x0, y: y0}
-            : null);
-        halfEdges.splice(iHalfEdge, 0, new d3_geom_voronoiHalfEdge(edge, cell.site, null));
+            : null), cell.site, null));
         ++nHalfEdges;
       }
     }