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

test/mjsunit/debug-constructor.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 57 matching lines @@
 assertEquals("accdca", call_graph);
 
 // Break point stops on "x = 1" and steps to "new c()" and then into c.
 Debug.setBreakPoint(b, 1);
 call_graph = "";
 b();
 Debug.clearStepping();  // Clear stepping as the listener leaves it on.
 assertEquals("bbccdcb", call_graph);
 
 // Get rid of the debug event listener.
-Debug.setListener(null);
+Debug.setListener(null);