Remove trailing whitespace.

Also adds a presubmit to prevent adding trailing whitespace to source
code in the future.

Change-Id: I41a4df81487f6f00aa19b188f0cac6a3377efde6
Reviewed-on: https://skia-review.googlesource.com/57380
Reviewed-by: Ravi Mistry <rmistry@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
diff --git a/experimental/tools/mskp_parser.py b/experimental/tools/mskp_parser.py
index 051e579..e9698f2 100755
--- a/experimental/tools/mskp_parser.py
+++ b/experimental/tools/mskp_parser.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 
 # Copyright 2016 Google Inc.
-# 
+#
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.