Keep refine menu enabled for views other than graph. (#286)

Pull request #263 disabled the refine menu for any views other than
Graph, but that's not expected - it's perfectly fine to use it for Flame
and Top, so just keep it enabled.

Fixes #285.

internal/driver/webhtml.go

   font-family: 'Roboto Medium', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
   position: relative;
 }
-.menu-item.disabled {
-  opacity: 0.5;
-}
 .menu-item .menu-name:hover {
   opacity: 0.75;
 }
 .menu-item .menu-name:hover .downArrow {
   border-top-color: #666;
 }
-.menu-item.disabled .menu-name:hover {
-  opacity: 1;
-}
-.menu-item.disabled .menu-name:hover .downArrow {
-  border-top-color: #ccc;
-}
 .menu-name {
   height: 100%;
   padding: 0 0.5em;
     </div>
   </div>
 
-  <div id="refine" class="menu-item disabled">
+  <div id="refine" class="menu-item">
     <div class="menu-name">
       Refine
       <i class="downArrow"></i>
         link.classList.toggle('disabled', !enable);
       }
     }
-    if (document.getElementById('graph') !== null) {
-      document.getElementById('refine').classList.remove('disabled');
-    }
   }
 
   // Initialize button states