Do more expensive check last

Since `isfile` does file IO, do it last.

Author: rchl

trailing_spaces.py

@@ -434,7 +434,7 @@ def freeze_last_version(self, view):
         file_name = view.file_name()
         # For some reasons, the on_activated hook gets fired on a ghost document
         # from time to time.
-        if file_name and isfile(file_name) and not view.is_scratch():
+        if file_name and not view.is_scratch() and isfile(file_name):
             on_disk = codecs.open(file_name, "r", "utf-8").read().splitlines()