Use clutter_event_get_* instead of ShellGlobal

Before Clutter gained accessors for event information, we had
shell_global_ functions.  Now that Clutter has them, use them and
delete the ShellGlobal code.

http://bugzilla.gnome.org/show_bug.cgi?id=594561

js/ui/runDialog.js

@@ -132,7 +132,7 @@ RunDialog.prototype = {
         }));
 
         this._entry.connect('key-press-event', Lang.bind(this, function(o, e) {
-            let symbol = Shell.get_event_key_symbol(e); 
+            let symbol = e.get_key_symbol();
             if (symbol == Clutter.Escape) {
                 this.close();
                 return true;