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

test/mjsunit/debug-setbreakpoint.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 196 matching lines @@
   assertTrue(!!i_script, "invalid script for i1");
   Debug.setScriptBreakPoint(Debug.ScriptBreakPointType.ScriptId,
                             i_script.id, 4);
 }
 
 // Creates the eval script and tries to set the breakpoint.
 // The tricky part is that the script function must be strongly reachable at the
 // moment. Since there's no way of simply getting the pointer to the function,
 // we run this code while the script function is being activated on stack.
 eval('SetBreakpointInI1Script()\nfunction i1(){}\n\n\n\nfunction i2(){}\n');
-