change combined pan-x pan-y to none

if both `pan-x` and `pan-y` are set (different recognizers for different
directions, e.g. horizontal pan but vertical swipe?) we need `none` (as
otherwise with `pan-x pan-y` combined none of these recognizers will
work, since the browser would handle all panning.

src/touchaction.js

@@ -126,9 +126,12 @@ function cleanTouchActions(actions) {
     var hasPanX = inStr(actions, TOUCH_ACTION_PAN_X);
     var hasPanY = inStr(actions, TOUCH_ACTION_PAN_Y);
 
-    // pan-x and pan-y can be combined
+    // if both pan-x and pan-y are set (different recognizers
+    // for different directions, e.g. horizontal pan but vertical swipe?)
+    // we need none (as otherwise with pan-x pan-y combined none of these
+    // recognizers will work, since the browser would handle all panning
     if (hasPanX && hasPanY) {
-        return TOUCH_ACTION_PAN_X + ' ' + TOUCH_ACTION_PAN_Y;
+        return TOUCH_ACTION_NONE;
     }
 
     // pan-x OR pan-y