loleaflet: Explicitly mention z-index to please MS Edge 40

This is not required in any other browser, but Edge 40 requires it
otherwise the popup window upon clicking the combo box goes behind the
main #map element.

Change-Id: Ie95263f08c8af27b16a56ba2c3c7a9faa308400a

loleaflet/dist/toolbar.css

@@ -42,6 +42,16 @@
     width: 100%;
 }
 
+/* For MS Edge 40, the select2 combo boxes need to have higher z-index than #map
+ * Ideal would be to add the class to select2-container <span>, but
+ * https://github.com/select2/select2/issues/285
+ * So, for now just define the z-index here separately for the same class that select2 uses
+ * as a container
+ */
+.select2-container {
+    z-index: 11;
+}
+
 /* center the toolbar */
 #tb_presentation-toolbar_item_left {
     width: 50%;