[JENKINS-13995]

Made the 'v' icon bigger to increase the hit test area, and improved the alignment
logic so that the text and the 'v' icon gets vertically aligned.

core/src/main/resources/lib/layout/breadcrumbs.css

@@ -53,8 +53,8 @@
   background-image: url(menu_down_arrow.png);
   background-position: center center;
   background-repeat: no-repeat;
-  width: 1em;
-  height:1em;
+  width: 15px;
+  height:16px;
   position: absolute;
   visibility: hidden;
   cursor: pointer;

core/src/main/resources/lib/layout/breadcrumbs.js

@@ -102,6 +102,7 @@ var breadcrumbs = (function() {
         menuSelector.show = function(target) {
             var xy = YAHOO.util.Dom.getXY(target);
             xy[0] += target.offsetWidth;
+            xy[1] += target.offsetHeight/2 - this.offsetHeight/2;
             YAHOO.util.Dom.setXY(this, xy);
             this.target = target;