Fixed updating axis margin after deleting group

src/timeline/component/ItemSet.js

@@ -748,6 +748,8 @@ ItemSet.prototype._onRemoveGroups = function _onRemoveGroups(ids) {
     }
   });
 
+  this.markDirty();
+
   this.emit('change');
 };
 

test/timeline_groups.html

@@ -12,7 +12,6 @@
     #visualization {
       box-sizing: border-box;
       width: 100%;
-      height: 300px;
     }
   </style>
 
@@ -75,7 +74,7 @@
   var options = {
     editable: {
       add: true,
-      //remove: true,
+      remove: true,
       updateTime: true,
       updateGroup: true
     },