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

test/mjsunit/debug-liveedit-3.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 48 matching lines @@
 var change_log = new Array();
 var result = Debug.LiveEdit.SetScriptSource(script, new_source, false, change_log);
 print("Result: " + JSON.stringify(result) + "\n");
 print("Change log: " + JSON.stringify(change_log) + "\n");
 
 assertEquals(8, z6());
 
 var z100 = Factory(100)();
 
 assertEquals(102, z100());
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