Change touchmove and touchstart listened element to 'document'

As for the mouse events, this allows to drag, zoom or rotate the map
with pointer(s) who moved outside of the viewport.

src/ol/mapbrowserevent.js

@@ -185,11 +185,11 @@ ol.MapBrowserEventHandler = function(map) {
       goog.events.EventType.TOUCHSTART,
       goog.events.EventType.MSPOINTERDOWN
     ], this.handleTouchStart_, false, this),
-    goog.events.listen(element, [
+    goog.events.listen(goog.global.document, [
       goog.events.EventType.TOUCHMOVE,
       goog.events.EventType.MSPOINTERMOVE
     ], this.handleTouchMove_, false, this),
-    goog.events.listen(element, [
+    goog.events.listen(goog.global.document, [
       goog.events.EventType.TOUCHEND,
       goog.events.EventType.MSPOINTERUP
     ], this.handleTouchEnd_, false, this)