Fix for bug 243027. shift+down arrow doesn't scroll

r=varga patch by neil


git-svn-id: svn://10.0.0.236/trunk@156140 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/toolkit/content/widgets/tree.xml

@@ -315,6 +315,7 @@
          } catch (e) {}
          // Extend the selection from the existing pivot, if any
          this.view.selection.rangedSelect(-1, c + 1, false);
+         this.treeBoxObject.ensureRowIsVisible(c + 1);
         ]]>
       </handler>
       <handler event="keypress" keycode="vk_up" modifiers="control">