Fix broken autocomplete popup when editing a saved search

https://forums.zotero.org/discussion/comment/345646/#Comment_345646

This is probably the actual fix for what I was trying to fix in
360f034b5, and I couldn't reproduce it because it was about saved
searches.

chrome/content/zotero/bindings/zoterosearch.xml

@@ -41,6 +41,12 @@
 		</resources>
 		
 		<implementation>
+			<constructor>
+			<![CDATA[
+				Components.utils.import("resource://gre/modules/Services.jsm");
+			]]>
+			</constructor>
+			
 			<property name="groups"/>
 			
 			<field name="searchRef"/>

components/zotero-autocomplete.js

@@ -32,7 +32,6 @@ const Ci = Components.interfaces;
 const Cr = Components.results;
 
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
-Components.utils.import("resource://gre/modules/Services.jsm");
 
 var Zotero = Components.classes["@zotero.org/Zotero;1"]
 	.getService(Components.interfaces.nsISupports)