[gnome-documents] documents: fix another undeclared variable runtime warning

[Cosimo Cecchi <cosimoc src gnome org>]

commit 98bd397780c62c65580c0556169c2e987ae3de07
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Fri Apr 19 12:37:11 2013 -0400

    documents: fix another undeclared variable runtime warning

 src/documents.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/documents.js b/src/documents.js
index 2d6ed16..4f0cbb8 100644
--- a/src/documents.js
+++ b/src/documents.js
@@ -927,7 +927,7 @@ const DocumentManager = new Lang.Class({
 
     clear: function() {
         let items = this.getItems();
-        for (idx in items) {
+        for (let idx in items) {
             items[idx].destroy();
         };