Fixed vertical scroll shadows becoming visible when dragging an item

lib/timeline/Core.js

@@ -93,7 +93,6 @@ Core.prototype._create = function (container) {
 
   this.on('rangechange', this.redraw.bind(this));
   this.on('touch',       this._onTouch.bind(this));
-  this.on('panstart',    this._onDragStart.bind(this));
   this.on('pan',         this._onDrag.bind(this));
 
   var me = this;
@@ -905,6 +904,7 @@ Core.prototype._stopAutoResize = function () {
  */
 Core.prototype._onTouch = function (event) {
   this.touch.allowDragging = true;
+  this.touch.initialScrollTop = this.props.scrollTop;
 };
 
 /**
@@ -916,15 +916,6 @@ Core.prototype._onPinch = function (event) {
   this.touch.allowDragging = false;
 };
 
-/**
- * Start moving the timeline vertically
- * @param {Event} event
- * @private
- */
-Core.prototype._onDragStart = function (event) {
-  this.touch.initialScrollTop = this.props.scrollTop;
-};
-
 /**
  * Move the timeline vertically
  * @param {Event} event