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

test/mjsunit/array-tostring.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 138 matching lines @@
       return 3;
     }});
 for (var i = 0; i < 3; i++) {
   Object.defineProperty(Number.prototype, i, {
       get: function() {
         assertEquals(expectedThis, this);
         return +this;
       }});
 }
 Number.prototype.arrayToLocaleString = Array.prototype.toLocaleString;
-assertEquals("42,42,42", (42).arrayToLocaleString());
+assertEquals("42,42,42", (42).arrayToLocaleString());