declare some variables before assigning them to avoid JS warnings

patch by Simon B��nzli
bug=342458
r=myk

browser/components/bookmarks/content/bookmarks.js

@@ -86,6 +86,10 @@ var kIOContractID;
 var kIOIID;
 var IOSVC;
 
+var kMICSUMContractID;
+var kMICSUMIID;
+var MICSUMSVC;
+
 var gBmProperties;
 var gBkmkTxnSvc;