fixed height of legend

lib/timeline/component/Legend.js

@@ -71,6 +71,7 @@ Legend.prototype._create = function() {
   this.svg.style.position = 'absolute';
   this.svg.style.top = 0 +'px';
   this.svg.style.width = this.options.iconSize + 5 + 'px';
+  this.svg.style.height = '100%';
 
   this.dom.frame.appendChild(this.svg);
   this.dom.frame.appendChild(this.dom.textArea);