Setting selectedIndex should clear all "previous value" state so that onchange

won't fire unless the user actually changes the value from the one set by
setting selectedIndex.  r=mats, sr=roc, a=roc


git-svn-id: svn://10.0.0.236/trunk@169304 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/layout/forms/nsListControlFrame.cpp

@@ -2205,7 +2205,9 @@ NS_IMETHODIMP
 nsListControlFrame::OnSetSelectedIndex(PRInt32 aOldIndex, PRInt32 aNewIndex)
 {
   if (mComboboxFrame) {
-    mComboboxFrame->UpdateRecentIndex(aOldIndex);
+    // UpdateRecentIndex with -1, so that we won't fire an onchange
+    // event for this setting of selectedIndex.
+    mComboboxFrame->UpdateRecentIndex(-1);
   }
 
   ScrollToIndex(aNewIndex);