Make sure files end with exactly one new line and police this in presubmit.

test/webkit/dfg-put-by-id-prototype-check.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 // 1.  Redistributions of source code must retain the above copyright
 //     notice, this list of conditions and the following disclaimer.
 // 2.  Redistributions in binary form must reproduce the above copyright
 //     notice, this list of conditions and the following disclaimer in the
@@ skipping 31 matching lines @@
         Foo.prototype.__defineSetter__("f", function(value) { stuff = value; });
 
     var o = new Foo();
     eval(Empty + "foo(o, i)");
     if (i >= 900) {
         shouldBe("stuff", "" + i);
         shouldBe("o.f", "" + (void 0));
     } else
         shouldBe("o.f", "" + i);
 }
-