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

test/mjsunit/str-to-num.js

 // Copyright 2008 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 193 matching lines @@
 
 for (var i = 1; i < 12; i++) {
   assertEquals(toNumber('1' + repeat('0', i)), Math.pow(10.0, i));
 }
 
 assertTrue(isNaN(toNumber("+0x0")));
 assertTrue(isNaN(toNumber("+0xFF")));
 assertTrue(isNaN(toNumber("+0x012")));
 assertTrue(isNaN(toNumber("-0x0")));
 assertTrue(isNaN(toNumber("-0xFF")));
-assertTrue(isNaN(toNumber("-0x012")));
+assertTrue(isNaN(toNumber("-0x012")));