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

test/mjsunit/object-literal-conversions.js

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 25 matching lines @@
 assertEquals(7, test1[13]);
 assertEquals(7, test2[13]);
 assertEquals(7, test3[13]);
 assertEquals(7, test4[13.213]);
 
 var test5 = { 13: function() {}, "13": 7 };
 var test6 = { 17.31: function() {}, "17.31": 7 };
 
 assertEquals(7, test5[13]);
 assertEquals(7, test6[17.31]);
-