Address review comments nits. r=thunder

services/sync/modules/engines/bookmarks.js

@@ -321,7 +321,7 @@ BookmarksStore.prototype = {
     // Do some post-processing if we have an item
     let itemId = idForGUID(record.id);
     if (itemId > 0) {
-      // Move any children that is looking for this folder as a parent
+      // Move any children that are looking for this folder as a parent
       if (record.type == "folder")
         this._reparentOrphans(itemId);
 

services/sync/modules/engines/forms.js

@@ -72,7 +72,7 @@ FormEngine.prototype = {
     this._store.clearFormCache();
     
     // Only leave 1 month's worth of form history
-    this._delete.older = this.lastSync - 2592000;
+    this._delete.older = this.lastSync - 2592000; // 60*60*24*30
     SyncEngine.prototype._syncFinish.call(this);
   },
 

services/sync/modules/engines/history.js

@@ -86,7 +86,7 @@ HistoryEngine.prototype = {
 
   _syncFinish: function HistEngine__syncFinish(error) {
     // Only leave 1 week's worth of history on the server
-    this._delete.older = this.lastSync - 604800;
+    this._delete.older = this.lastSync - 604800; // 60*60*24*7
     SyncEngine.prototype._syncFinish.call(this);
   },