Optimise.

This block is only necessary if there are remaining touches, because
otherwise the gesture has ended and we remove this closure along with
locations0.  Thanks, @mbostock!

d3.js

@@ -1407,11 +1407,11 @@ d3 = function() {
         zoomed(event_);
       }
       function ended() {
-        var touches = d3.event.changedTouches;
-        for (var i = 0, n = touches.length; i < n; ++i) {
-          delete locations0[touches[i].identifier];
-        }
         if (d3.event.touches.length) {
+          var touches = d3.event.changedTouches;
+          for (var i = 0, n = touches.length; i < n; ++i) {
+            delete locations0[touches[i].identifier];
+          }
           relocate();
         } else {
           w.on(touchmove, null).on(touchend, null);

src/behavior/zoom.js

@@ -261,11 +261,11 @@ d3.behavior.zoom = function() {
     }
 
     function ended() {
-      var touches = d3.event.changedTouches;
-      for (var i = 0, n = touches.length; i < n; ++i) {
-        delete locations0[touches[i].identifier];
-      }
       if (d3.event.touches.length) {
+        var touches = d3.event.changedTouches;
+        for (var i = 0, n = touches.length; i < n; ++i) {
+          delete locations0[touches[i].identifier];
+        }
         relocate(); // locations may have detached due to rotation
       } else {
         w.on(touchmove, null).on(touchend, null);