style(tooltip): removed comment and extrated sort

public/app/plugins/panels/graph/graph.tooltip.js

@@ -126,10 +126,7 @@ function ($) {
         relativeTime = dashboard.getRelativeTime(seriesHoverInfo.time);
         absoluteTime = dashboard.formatDate(seriesHoverInfo.time);
 
-	// Dynamically reorder the hovercard for the current time point.
-        seriesHoverInfo.sort(function(a, b) {
-          return parseFloat(b.value) - parseFloat(a.value);
-        });
+        seriesHoverInfo.sort(byToolTipValue);
 
         for (i = 0; i < seriesHoverInfo.length; i++) {
           hoverInfo = seriesHoverInfo[i];
@@ -179,5 +176,9 @@ function ($) {
     });
   }
 
+  function byToolTipValue(a, b) {
+    return parseFloat(b.value) - parseFloat(a.value);
+  }
+
   return GraphTooltip;
 });