Replace PointerMap with polyfill for regular Map

src/dispatcher.js

@@ -1,4 +1,4 @@
-import PointerMap from 'pointermap';
+import Map from 'map';
 
 var CLONE_PROPS = [
 
@@ -99,7 +99,7 @@ var HAS_SVG_INSTANCE = (typeof SVGElementInstance !== 'undefined');
  *   - pointercancel: a pointer will no longer generate events
  */
 var dispatcher = {
-  pointermap: new PointerMap(),
+  pointermap: new Map(),
   eventMap: Object.create(null),
   captureInfo: Object.create(null),
 

src/pointermap.js → src/map.js

@@ -1,20 +1,17 @@
 /**
  * This module implements an map of pointer states
  */
-var USE_MAP = window.Map && window.Map.prototype.forEach;
-var POINTERS_FN = function() { return this.size; };
-function PointerMap() {
-  if (USE_MAP) {
-    var m = new Map();
-    m.pointers = POINTERS_FN;
-    return m;
+var USE_EXISTING_MAP = window.Map && window.Map.prototype.forEach;
+function Map() {
+  if (USE_EXISTING_MAP) {
+    return new Map();
   } else {
     this.keys = [];
     this.values = [];
   }
 }
 
-PointerMap.prototype = {
+Map.prototype = {
   set: function(inId, inEvent) {
     var i = this.keys.indexOf(inId);
     if (i > -1) {
@@ -49,9 +46,9 @@ PointerMap.prototype = {
       callback.call(thisArg, v, this.keys[i], this);
     }, this);
   },
-  pointers: function() {
+  get size() {
     return this.keys.length;
   }
 };
 
-export default PointerMap;
+export default Map;

src/touch.js

@@ -112,7 +112,7 @@ var touchEvents = {
   setPrimaryTouch: function(inTouch) {
 
     // set primary touch if there no pointers, or the only pointer is the mouse
-    if (pointermap.pointers() === 0 || (pointermap.pointers() === 1 && pointermap.has(1))) {
+    if (pointermap.size() === 0 || (pointermap.size() === 1 && pointermap.has(1))) {
       this.firstTouch = inTouch.identifier;
       this.firstXY = { X: inTouch.clientX, Y: inTouch.clientY };
       this.scrolling = false;
@@ -233,9 +233,9 @@ var touchEvents = {
   vacuumTouches: function(inEvent) {
     var tl = inEvent.touches;
 
-    // pointermap.pointers() should be < tl.length here, as the touchstart has not
+    // pointermap.size() should be < tl.length here, as the touchstart has not
     // been processed yet.
-    if (pointermap.pointers() >= tl.length) {
+    if (pointermap.size() >= tl.length) {
       var d = [];
       pointermap.forEach(function(value, key) {