fix: pass actual position of contextmenu to callback

Before the position a user has started to open the contextmenu, has been passed to
callback even if the user has moved the map while opening the contextmenu. In these
case the position of contextmenu on map, differed from the position which as passed
to callback function.

Before 212a57f this bug could only occure if user
has opened the contextmenu using a touch input. If using a mouse, contextmenu would
have been closed if user moved the map while opening contextmenu.

dist/leaflet.contextmenu.js

@@ -29,14 +29,14 @@ L.Map.mergeOptions({
 
 L.Map.ContextMenu = L.Handler.extend({
     _touchstart: L.Browser.msPointer ? 'MSPointerDown' : L.Browser.pointer ? 'pointerdown' : 'touchstart',
-    
+
     statics: {
         BASE_CLS: 'leaflet-contextmenu'
     },
-    
+
     initialize: function (map) {
         L.Handler.prototype.initialize.call(this, map);
-        
+
         this._items = [];
         this._visible = false;
 
@@ -318,12 +318,24 @@ L.Map.ContextMenu = L.Handler.extend({
                 return;
             }
 
+            var map = me._map,
+                containerPoint = me._showLocation.containerPoint,
+                layerPoint = map.containerPointToLayerPoint(containerPoint),
+                latlng = map.layerPointToLatLng(layerPoint),
+                relatedTarget = me._showLocation.relatedTarget,
+                data = {
+                  containerPoint: containerPoint,
+                  layerPoint: layerPoint,
+                  latlng: latlng,
+                  relatedTarget: relatedTarget
+                };
+
             if (hideOnSelect) {
                 me._hide();
             }
 
             if (func) {
-                func.call(context || map, me._showLocation);
+                func.call(context || map, data);
             }
 
             me._map.fire('contextmenu.select', {
@@ -359,13 +371,9 @@ L.Map.ContextMenu = L.Handler.extend({
     _showAtPoint: function (pt, data) {
         if (this._items.length) {
             var map = this._map,
-            layerPoint = map.containerPointToLayerPoint(pt),
-            latlng = map.layerPointToLatLng(layerPoint),
             event = L.extend(data || {}, {contextmenu: this});
 
             this._showLocation = {
-                latlng: latlng,
-                layerPoint: layerPoint,
                 containerPoint: pt
             };