chore: improve snippet for clarity

It did work in the past, albeit with some magic involved (element was retrieve from closure).

This one is better, I believe.

lib/features/context-pad/ContextPadProvider.js

@@ -154,7 +154,7 @@ ContextPadProvider.prototype.getContextPadEntries = function(element) {
     connect.start(event, element);
   }
 
-  function removeElement(e) {
+  function removeElement(e, element) {
     modeling.removeElements([ element ]);
   }