Return the correct "buttons" value for touch

Fixes #130

Clear out `ev` variable to release MouseEvent test

src/PointerEvent.js

@@ -26,6 +26,7 @@
     var ev = new MouseEvent('click', {buttons: 1});
     NEW_MOUSE_EVENT = true;
     HAS_BUTTONS = ev.buttons === 1;
+    ev = null;
   } catch(e) {
   }
 
@@ -86,10 +87,9 @@
     // is to call initMouseEvent with a buttonArg value of -1.
     //
     // This is fixed with DOM Level 4's use of buttons
-    var buttons;
-    if (inDict.buttons || HAS_BUTTONS) {
-      buttons = inDict.buttons;
-    } else {
+    var buttons = inDict.buttons;
+    // touch has two possible buttons state: 0 and 1, rely on being told the right one
+    if (!HAS_BUTTONS && inType !== 'touch') {
       switch (inDict.which) {
         case 1: buttons = 1; break;
         case 2: buttons = 4; break;

src/touch.js

@@ -137,6 +137,13 @@
         clearTimeout(this.resetId);
       }
     },
+    typeToButtons: function(type) {
+      var ret = 0;
+      if (type === 'touchstart' || type === 'touchmove') {
+        ret = 1;
+      }
+      return ret;
+    },
     touchToPointer: function(inTouch) {
       var e = dispatcher.cloneEvent(inTouch);
       // Spec specifies that pointerId 1 is reserved for Mouse.
@@ -148,7 +155,7 @@
       e.cancelable = true;
       e.detail = this.clickCount;
       e.button = 0;
-      e.buttons = 1;
+      e.buttons = this.typeToButtons(this.currentTouchEvent);
       e.width = inTouch.webkitRadiusX || inTouch.radiusX || 0;
       e.height = inTouch.webkitRadiusY || inTouch.radiusY || 0;
       e.pressure = inTouch.webkitForce || inTouch.force || 0.5;
@@ -158,6 +165,7 @@
     },
     processTouches: function(inEvent, inFunction) {
       var tl = inEvent.changedTouches;
+      this.currentTouchEvent = inEvent.type;
       var pointers = touchMap(tl, this.touchToPointer, this);
       // forward touch preventDefaults
       pointers.forEach(function(p) {