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

test/mjsunit/regress/regress-crbug-3184.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 62 matching lines @@
     if (typeof fun != "function") throw new TypeError();
     var len = this.length;
     var res = new Array(len);
     var thisp = arguments[1];
     for (var i = 0; i < len; i++) { if (i in this) res[i] = fun.call(thisp, this[i], i, this); }
     return res;
   }
 });
 assertEquals("Test1 test1", "test1 test1".cap());
 assertEquals("Test2 Test2", "test2 test2".cap(true));
-