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

test/webkit/fast/js/JSON-parse-reviver.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 // 1.  Redistributions of source code must retain the above copyright
 //     notice, this list of conditions and the following disclaimer.
 // 2.  Redistributions in binary form must reproduce the above copyright
 //     notice, this list of conditions and the following disclaimer in the
@@ skipping 183 matching lines @@
 var createdBadness = false;
 function reviveIntroducesNewArrayLikeObject(i, v) {
     if (i == 0 && !createdBadness) {
         this[1] = /(a)+/.exec("a");
         createdBadness = true;
     }
     return v;
 }
 
 shouldBe('JSON.stringify(JSON.parse("[0,1]", reviveIntroducesNewArrayLikeObject))', '\'[0,["a","a"]]\'');
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