Properly fix SF bug #507298 (Gregor Lingl): shellpython2.2 -Qnew smart
indent error

Use // where int division is intended.  (This breaks IDLE for use with
previous Python versions -- I don't care.)
diff --git a/Tools/idle/EditorWindow.py b/Tools/idle/EditorWindow.py
index bb69a5b..f924c45 100644
--- a/Tools/idle/EditorWindow.py
+++ b/Tools/idle/EditorWindow.py
@@ -465,7 +465,7 @@
         top, bot = self.getwindowlines()
         lineno = self.getlineno(mark)
         height = bot - top
-        newtop = max(1, lineno - height/2)
+        newtop = max(1, lineno - height//2)
         text.yview(float(newtop))
 
     def getwindowlines(self):