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

test/mjsunit/regress/regress-1246.js

 // Copyright 2011 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 62 matching lines @@
   assertEquals(NaN, parseInt("af", radix));
 }
 
 for (var i = 0; i < radix16.length; i++) {
   var radix = radix16[i];
   assertEquals(NaN, parseInt("", radix));
   assertEquals(0x23, parseInt("23", radix));
   assertEquals(0xaf, parseInt("0xaf", radix));
   assertEquals(0xaf, parseInt("af", radix));
 }
-