Fix initial load when options start and end are not defined (#3664)

lib/timeline/Timeline.js

@@ -184,7 +184,7 @@ function Timeline (container, items, groups, options) {
   //Single time autoscale/fit
   this.initialFitDone = false;
   this.on('changed', function (){
-    if (this.itemsData == null || this.options.rollingMode) return;
+    if (me.itemsData == null || me.options.rollingMode) return;
     if (!me.initialFitDone) {
       me.initialFitDone = true;
       if (me.options.start != undefined || me.options.end != undefined) {
@@ -200,7 +200,7 @@ function Timeline (container, items, groups, options) {
       }
     }
 
-    if (!me.initialDrawDone && me.initialRangeChangeDone) {
+    if (!me.initialDrawDone && (me.initialRangeChangeDone || (!me.options.start && !me.options.end))) {
       me.initialDrawDone = true;
       me.dom.root.style.visibility = 'visible';
       me.dom.loadingScreen.parentNode.removeChild(me.dom.loadingScreen);