Index: node_modules/d3-polygon/src/hull.js
===================================================================
--- node_modules/d3-polygon/src/hull.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-polygon/src/hull.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,49 @@
+import cross from "./cross.js";
+
+function lexicographicOrder(a, b) {
+  return a[0] - b[0] || a[1] - b[1];
+}
+
+// Computes the upper convex hull per the monotone chain algorithm.
+// Assumes points.length >= 3, is sorted by x, unique in y.
+// Returns an array of indices into points in left-to-right order.
+function computeUpperHullIndexes(points) {
+  const n = points.length,
+      indexes = [0, 1];
+  let size = 2, i;
+
+  for (i = 2; i < n; ++i) {
+    while (size > 1 && cross(points[indexes[size - 2]], points[indexes[size - 1]], points[i]) <= 0) --size;
+    indexes[size++] = i;
+  }
+
+  return indexes.slice(0, size); // remove popped points
+}
+
+export default function(points) {
+  if ((n = points.length) < 3) return null;
+
+  var i,
+      n,
+      sortedPoints = new Array(n),
+      flippedPoints = new Array(n);
+
+  for (i = 0; i < n; ++i) sortedPoints[i] = [+points[i][0], +points[i][1], i];
+  sortedPoints.sort(lexicographicOrder);
+  for (i = 0; i < n; ++i) flippedPoints[i] = [sortedPoints[i][0], -sortedPoints[i][1]];
+
+  var upperIndexes = computeUpperHullIndexes(sortedPoints),
+      lowerIndexes = computeUpperHullIndexes(flippedPoints);
+
+  // Construct the hull polygon, removing possible duplicate endpoints.
+  var skipLeft = lowerIndexes[0] === upperIndexes[0],
+      skipRight = lowerIndexes[lowerIndexes.length - 1] === upperIndexes[upperIndexes.length - 1],
+      hull = [];
+
+  // Add upper hull in right-to-l order.
+  // Then add lower hull in left-to-right order.
+  for (i = upperIndexes.length - 1; i >= 0; --i) hull.push(points[sortedPoints[upperIndexes[i]][2]]);
+  for (i = +skipLeft; i < lowerIndexes.length - skipRight; ++i) hull.push(points[sortedPoints[lowerIndexes[i]][2]]);
+
+  return hull;
+}